Consolidated Balance Sheet
| Concept | As at 2024-03-31 | As at 2023-06-30 | 
|---|---|---|
| Consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Non-current assets | ||
| Property, plant and equipment | ||
| Property, plant and equipment | 
                                                1,787,788,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,863,996,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Intangible assets | 
                                                356,120,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                373,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investment securities | 
                                                676,776,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                515,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax assets | 
                                                74,967,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                69,774,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                892,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                967,664,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit asset | 
                                                3,256,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,215,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                4,900,383,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,769,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                7,044,292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,006,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | ||
| Cash and deposits | 
                                                2,627,593,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,266,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Notes and accounts receivable - trade | 
                                                3,376,668,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,407,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Contract assets | 
                                                15,888,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,939,461,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                396,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                403,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                22,289,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,018,293,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                29,333,533,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,025,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Non-current liabilities | 
                                                1,982,506,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,280,530,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Long-term borrowings | 
                                                714,292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                882,005,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit liability | 
                                                454,030,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                403,244,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                122,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                123,779,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax liabilities | 
                                                623,979,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                788,232,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                15,336,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,888,443,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                8,300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                17,319,489,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,168,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                11,379,763,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,331,977,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                2,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                1,609,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,582,321,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                7,799,120,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,827,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -28,494,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -77,428,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                617,626,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                507,579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation difference on available-for-sale securities | 
                                                334,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                207,391,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                -16,545,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -16,333,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                16,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                12,014,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,856,211,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                29,333,533,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,025,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Non-current liabilities | ||
| Provision for retirement benefits for directors (and other officers) | 
                                                50,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                68,005,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                83,268,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | ||
| Current portion of long-term borrowings | 
                                                214,284,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                220,284,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                557,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                493,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provisions | ||
| Provision for bonuses | 
                                                850,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,428,597,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,069,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Valuation and translation adjustments | ||
| Remeasurements of defined benefit plans | 
                                                299,890,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                316,521,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |