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 | — | — | 
                                                381,661,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                373,683,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                119,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,535,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                382,218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                382,337,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -675,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                363,760,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                90,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -484,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                355,493,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                363,366,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,267,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                363,851,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary income | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other operating income | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Share of profit of entities accounted for using equity method | — | — | 
                                                400,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                183,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cost of sales | — | — | 
                                                310,015,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                303,419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Operating expenses | ||||||||||||||||||||||||||||
| Selling, general and administrative expenses | — | — | 
                                                39,231,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                27,373,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                24,805,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                35,755,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Depreciation | — | — | 
                                                2,615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,946,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,518,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,086,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Taxes and dues | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,042,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                765,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Provision of allowance for doubtful accounts | — | — | 
                                                122,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                -22,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other | — | — | 
                                                14,412,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                12,980,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Operating expenses | ||||||||||||||||||||||||||||
| Other operating expenses | ||||||||||||||||||||||||||||
| Operating expenses | ||||||||||||||||||||||||||||
| Operating expenses | ||||||||||||||||||||||||||||
| Operating expenses - general | ||||||||||||||||||||||||||||
| Remuneration for directors (and other officers) | — | — | — | — | — | — | — | — | — | — | — | 
                                                299,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                285,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Welfare expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                533,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                885,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Rent expenses on land and buildings | — | — | 
                                                2,740,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2,227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,674,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Operating profit (loss) | — | — | 
                                                32,415,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                31,738,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                82,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                579,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,317,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,400,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,151,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                51,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -10,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                20,898,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,745,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                405,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net sales | ||||||||||||||||||||||||||||
| Net sales of completed construction contracts | — | — | — | — | — | — | — | — | — | — | — | 
                                                274,274,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                268,657,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Operating expenses | ||||||||||||||||||||||||||||
| Research and development expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,747,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2,662,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Ordinary profit (loss) | — | — | 
                                                34,970,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                32,045,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                22,988,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                26,150,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Gross profit (loss) | — | — | 
                                                71,646,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                59,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| General and administrative expenses | ||||||||||||||||||||||||||||
| Salaries | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Donations | — | — | — | — | — | — | — | — | — | — | — | 
                                                57,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                69,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Non-operating income | ||||||||||||||||||||||||||||
| Interest income | — | — | 
                                                549,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                17,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                413,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividend income | — | — | 
                                                926,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,018,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,605,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                784,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other | — | — | 
                                                761,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                643,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                528,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,002,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Non-operating income | — | — | 
                                                3,628,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                3,672,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                3,262,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,421,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cost of sales | ||||||||||||||||||||||||||||
| Cost of sales of completed construction contracts | — | — | — | — | — | — | — | — | — | — | — | 
                                                217,765,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                222,953,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Selling, general and administrative expenses | ||||||||||||||||||||||||||||
| Employees' salaries and allowances | — | — | 
                                                11,149,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                5,999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                5,541,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,598,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Legal welfare expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                978,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                981,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Advertising expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,137,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,092,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Repair and maintenance expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                164,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                165,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Stationery expenses | — | — | 
                                                3,716,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                3,243,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                3,153,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Communication and transportation expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                995,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                858,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Power utilities expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                186,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                150,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Research study expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,157,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,676,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Entertainment expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                502,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                404,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Insurance expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                391,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                325,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Miscellaneous expenses | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,270,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,221,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Amortization of goodwill | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Extraordinary income | — | — | 
                                                2,714,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,366,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,309,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other | — | — | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Non-operating expenses | ||||||||||||||||||||||||||||
| Interest expenses | — | — | 
                                                269,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                103,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                110,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other | — | — | 
                                                182,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                145,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                358,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                472,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Non-operating expenses | — | — | 
                                                1,073,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                762,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,463,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Extraordinary losses | — | — | 
                                                176,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                162,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                378,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                407,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Impairment losses | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | — | — | 
                                                5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Profit (loss) before income taxes | — | — | 
                                                37,508,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                34,567,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                23,977,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                27,053,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Gross profit | ||||||||||||||||||||||||||||
| Gross profit (loss) on completed construction contracts | — | — | — | — | — | — | — | — | — | — | — | 
                                                56,509,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                45,703,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Extraordinary income | ||||||||||||||||||||||||||||
| Gain on sale of investment securities | — | — | 
                                                2,712,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,366,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,295,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes - current | — | — | 
                                                10,618,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                9,168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                7,092,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Extraordinary losses | ||||||||||||||||||||||||||||
| Loss on retirement of non-current assets | — | — | 
                                                27,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                17,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                67,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                96,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes - deferred | — | — | 
                                                -1,134,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -833,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                -1,048,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,414,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes | — | — | 
                                                9,484,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                8,334,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                6,043,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,942,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Profit (loss) | — | — | 
                                                28,024,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                26,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                26,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                17,933,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,933,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                17,933,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                20,111,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,933,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to non-controlling interests | — | — | 
                                                392,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                498,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Profit (loss) attributable to owners of parent | 
                                                27,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                27,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                27,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                19,612,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                19,612,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                19,612,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Profit attributable to | ||||||||||||||||||||||||||||
| Other comprehensive income | ||||||||||||||||||||||||||||
| Valuation difference on available-for-sale securities | — | — | 
                                                -1,617,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                5,558,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Foreign currency translation adjustment | — | — | 
                                                1,006,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,266,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share of other comprehensive income of entities accounted for using equity method | — | — | 
                                                33,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                224,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Remeasurements of defined benefit plans, net of tax | — | — | 
                                                109,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,052,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other comprehensive income | — | — | 
                                                -467,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,101,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Comprehensive income | — | — | 
                                                27,556,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                29,212,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Comprehensive income attributable to | ||||||||||||||||||||||||||||
| Comprehensive income attributable to owners of parent | — | — | 
                                                26,771,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                28,638,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Comprehensive income attributable to non-controlling interests | — | — | 
                                                785,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                573,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — |