Consolidated Balance Sheet
| Concept | As at 2024-03-31 | As at 2023-06-30 | 
|---|---|---|
| Consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                1,919,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,224,862,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Notes receivable, accounts receivable from completed construction contracts and other | 
                                                1,930,017,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,218,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Supplies | 
                                                1,367,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                35,658,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                28,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                4,146,458,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,732,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                751,870,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                738,725,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Intangible assets | ||
| Intangible assets | 
                                                24,532,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Other | 
                                                435,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                400,274,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -22,488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -22,488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                413,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                377,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                1,189,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,134,710,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                5,336,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,867,611,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Notes payable, accounts payable for construction contracts and other | 
                                                1,014,969,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                790,671,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                61,907,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                76,557,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Advances received on construction contracts in progress | 
                                                228,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                662,021,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provisions | ||
| Provision for bonuses | 
                                                34,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                99,408,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                151,784,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,943,207,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,687,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Retirement benefit liability | 
                                                14,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                98,036,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                68,351,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                112,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                82,878,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                2,055,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,770,613,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Shareholders' equity | 
                                                3,140,739,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,979,668,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                849,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                849,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                635,388,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                630,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                1,811,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,665,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -155,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -166,587,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                101,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                86,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation difference on available-for-sale securities | 
                                                101,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                86,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-controlling interests | 
                                                37,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                3,280,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,096,998,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                5,336,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,867,611,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Valuation and translation adjustments |