Consolidated Statement Of Income
| Concept | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Consolidated statement of income | ||||||||||||||||||||||||||||
| Statement of income | ||||||||||||||||||||||||||||
| Net sales | — | 
                                                28,384,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                39,283,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,647,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                69,557,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                341,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,313,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,694,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,654,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,097,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                68,619,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,453,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                740,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,017,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                39,149,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,411,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                61,980,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                67,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                69,358,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary income | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other operating income | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Share of profit of entities accounted for using equity method | — | — | — | — | — | 
                                                180,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                60,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cost of sales | — | — | — | — | — | 
                                                57,548,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                52,788,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                52,479,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                57,133,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Operating expenses | ||||||||||||||||||||||||||||
| Operating expenses - general | ||||||||||||||||||||||||||||
| Remuneration for directors (and other officers) | — | — | — | — | — | — | — | — | — | — | — | 
                                                192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                183,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Welfare expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                323,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                339,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Rent expenses on land and buildings | — | — | — | — | — | — | — | — | — | — | — | 
                                                305,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                305,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Taxes and dues | — | — | — | — | — | — | — | — | — | — | — | 
                                                65,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                70,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Depreciation | — | — | — | — | — | — | — | — | — | — | — | 
                                                355,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                340,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Operating expenses | ||||||||||||||||||||||||||||
| Selling, general and administrative expenses | — | — | — | — | — | 
                                                8,832,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                7,836,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                7,172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,158,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Provision of allowance for doubtful accounts | — | — | — | — | — | 
                                                20,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                19,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -19,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other | — | — | — | — | — | 
                                                4,574,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,488,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Operating expenses | ||||||||||||||||||||||||||||
| Other operating expenses | ||||||||||||||||||||||||||||
| Operating expenses | ||||||||||||||||||||||||||||
| Gross profit (loss) | — | — | — | — | — | 
                                                12,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,906,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,501,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,814,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                3,366,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,037,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,524,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| General and administrative expenses | ||||||||||||||||||||||||||||
| Salaries | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Donations | — | — | — | — | — | — | — | — | — | — | — | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                12,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Operating profit (loss) | — | 
                                                559,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,395,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,177,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,016,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,070,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,038,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -861,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,634,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,496,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,060,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -10,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,329,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,656,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,665,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Operating expenses | ||||||||||||||||||||||||||||
| Net sales | ||||||||||||||||||||||||||||
| Net sales of completed construction contracts | — | — | — | — | — | 
                                                66,379,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                61,265,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                58,573,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net sales in sideline businesses | — | — | — | — | — | 
                                                3,177,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,428,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,407,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cost of sales | ||||||||||||||||||||||||||||
| Cost of sales of completed construction contracts | — | — | — | — | — | 
                                                55,647,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                51,327,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                50,272,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,367,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cost of sales in sideline businesses | — | — | — | — | — | 
                                                1,901,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,461,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,206,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,766,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Selling, general and administrative expenses | ||||||||||||||||||||||||||||
| Employees' salaries and allowances | — | — | — | — | — | 
                                                2,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,606,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,570,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,874,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Advertising expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                65,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                65,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Legal welfare expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                552,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                498,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repair and maintenance expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                114,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Stationery expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                230,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                207,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Communication and transportation expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                402,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Power utilities expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                25,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                24,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Research study expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                437,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Entertainment expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                150,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                151,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Insurance expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                23,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                21,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Miscellaneous expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                198,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                186,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Amortization of goodwill | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-operating income | ||||||||||||||||||||||||||||
| Interest income | — | — | — | — | — | 
                                                37,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                15,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                33,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividend income | — | — | — | — | — | 
                                                187,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                120,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                146,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other | — | — | — | — | — | 
                                                32,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                16,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Non-operating income | — | — | — | — | — | 
                                                449,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                207,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                309,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                412,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Extraordinary income | — | — | — | — | — | 
                                                60,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                44,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                996,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Extraordinary losses | — | — | — | — | — | 
                                                117,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                50,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Non-operating expenses | ||||||||||||||||||||||||||||
| Interest expenses | — | — | — | — | — | 
                                                74,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                69,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                67,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other | — | — | — | — | — | 
                                                20,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Non-operating expenses | — | — | — | — | — | 
                                                260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                239,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                113,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                121,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Profit (loss) before income taxes | — | — | — | — | — | 
                                                3,310,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,953,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,470,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,970,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Gross profit | ||||||||||||||||||||||||||||
| Gross profit (loss) on completed construction contracts | — | — | — | — | — | 
                                                10,732,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9,938,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                8,300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,326,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Gross profit (loss) on sideline businesses | — | — | — | — | — | 
                                                1,277,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                968,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,201,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,489,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Extraordinary income | ||||||||||||||||||||||||||||
| Gain on sale of non-current assets | — | — | — | — | — | 
                                                60,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                44,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                69,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Gain on sale of investment securities | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes - current | — | — | — | — | — | 
                                                1,251,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,097,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,006,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,129,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes - deferred | — | — | — | — | — | 
                                                -151,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -157,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -163,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -185,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Extraordinary losses | ||||||||||||||||||||||||||||
| Loss on sale of non-current assets | — | — | — | — | — | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Loss on retirement of non-current assets | — | — | — | — | — | 
                                                4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                50,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                53,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes | — | — | — | — | — | 
                                                1,100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                941,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                843,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                944,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Profit (loss) | — | — | — | — | 
                                                2,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,210,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                2,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to non-controlling interests | — | — | — | — | — | 
                                                8,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                17,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Profit (loss) attributable to owners of parent | 
                                                2,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                2,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other comprehensive income | ||||||||||||||||||||||||||||
| Valuation difference on available-for-sale securities | — | — | — | — | — | 
                                                117,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                225,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Foreign currency translation adjustment | — | — | — | — | — | 
                                                175,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                81,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Remeasurements of defined benefit plans, net of tax | — | — | — | — | — | 
                                                64,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other comprehensive income | — | — | — | — | — | 
                                                356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                312,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Profit attributable to | ||||||||||||||||||||||||||||
| Comprehensive income | — | — | — | — | — | 
                                                2,565,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,338,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Comprehensive income attributable to | ||||||||||||||||||||||||||||
| Comprehensive income attributable to owners of parent | — | — | — | — | — | 
                                                2,555,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,317,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Comprehensive income attributable to non-controlling interests | — | — | — | — | — | 
                                                10,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                22,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — |