Consolidated Balance Sheet
| Concept | As at 2024-09-30 | As at 2024-03-31 | 
|---|---|---|
| Consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Non-current assets | 
                                                15,144,271,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,908,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                5,619,913,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,804,562,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investment securities | 
                                                3,816,138,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,356,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Long-term loans receivable | 
                                                13,370,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,215,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax assets | 
                                                59,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,722,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,732,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,425,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -208,150,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -209,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | ||
| Cash and deposits | 
                                                9,125,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,983,888,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Securities | 
                                                99,984,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                199,736,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Notes receivable, accounts receivable from completed construction contracts and other | 
                                                17,249,564,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,826,308,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Costs on construction contracts in progress | 
                                                268,774,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                262,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                536,986,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                740,742,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -166,870,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -83,694,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                29,288,605,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,862,658,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                7,074,918,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,790,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                4,581,808,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,427,793,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Construction in progress | 
                                                149,467,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                122,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | 
                                                4,134,991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,161,398,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Own-used assets | ||
| Machinery, equipment and vehicles | 
                                                1,943,475,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,777,876,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                494,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                441,132,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -4,228,876,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,139,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Goodwill | 
                                                1,209,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,260,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                512,386,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                271,491,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other intangible assets | ||
| Intangible assets | 
                                                2,449,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,312,711,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Retirement benefit asset | 
                                                206,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                191,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                44,432,876,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,770,852,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Notes payable, accounts payable for construction contracts and other | 
                                                5,146,648,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,604,093,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                2,078,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                589,354,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                412,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provisions | ||
| Provision for bonuses | 
                                                361,061,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                506,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Advances received on construction contracts in progress | 
                                                5,521,352,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,081,676,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,030,498,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,722,700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                16,500,209,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,651,501,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Deferred tax liabilities | 
                                                357,220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                263,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                543,220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                404,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                186,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                141,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                17,043,430,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,056,276,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Shareholders' equity | 
                                                24,296,498,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,534,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                5,086,553,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,541,951,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                16,933,879,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,566,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -2,918,992,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,768,329,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                3,091,773,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,174,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation difference on available-for-sale securities | 
                                                1,182,270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                990,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                1,889,409,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,159,429,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                1,173,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                27,389,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,714,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                44,432,876,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,770,852,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Valuation and translation adjustments | ||
| Remeasurements of defined benefit plans | 
                                                20,093,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |