Consolidated Balance Sheet
| Concept | As at 2023-12-31 | As at 2023-03-31 | 
|---|---|---|
| Consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                8,694,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,799,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Notes receivable, accounts receivable from completed construction contracts and other | 
                                                5,475,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accounts receivable - other | 
                                                1,380,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                862,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Contract assets | 
                                                20,093,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,462,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                2,763,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,071,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                913,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,083,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -84,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -90,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                42,483,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,876,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                13,131,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,252,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                3,926,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,845,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investment securities | 
                                                2,600,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,287,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -96,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -96,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,421,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,653,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | ||
| Property, plant and equipment | 
                                                8,394,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,460,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Intangible assets | 
                                                811,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Assets | 
                                                55,614,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Notes payable, accounts payable for construction contracts and other | 
                                                8,070,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,600,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                4,886,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,521,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                192,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,068,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provisions | ||
| Provisions | 
                                                722,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                801,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,343,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,429,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                20,994,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,755,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Long-term borrowings | 
                                                50,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit liability | 
                                                789,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                761,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Lease liabilities | 
                                                600,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                538,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provisions | ||
| Provisions | 
                                                80,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                86,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                41,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                34,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                1,560,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,525,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                22,554,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Shareholders' equity | 
                                                32,011,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,198,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                14,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                13,870,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,060,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -1,615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,619,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                601,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                222,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation difference on available-for-sale securities | 
                                                393,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                229,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                249,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-controlling interests | 
                                                448,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                428,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                33,060,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,848,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                55,614,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Valuation and translation adjustments | ||
| Remeasurements of defined benefit plans | 
                                                -41,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -45,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |