Quarterly Consolidated Balance Sheet
| Concept | As at 2025-03-31 | As at 2024-09-30 | 
|---|---|---|
| Quarterly consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                1,751,247,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,965,997,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                1,248,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,792,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                70,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                280,610,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -2,045,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -13,974,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                7,666,964,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,415,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                929,625,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                789,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | — | — | 
| Buildings and structures, net | 
                                                141,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                143,802,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles | — | — | 
| Machinery, equipment and vehicles, net | 
                                                335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                701,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                194,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                194,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets | — | — | 
| Leased assets, net | 
                                                1,816,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,137,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Construction in progress | 
                                                582,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                442,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Goodwill | 
                                                491,777,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                655,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                192,855,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                119,499,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | 
                                                684,632,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                774,701,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                234,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                235,355,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Deferred tax assets | 
                                                113,566,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                113,566,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                121,391,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                121,889,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                1,849,116,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,799,784,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                9,516,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,215,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Short-term borrowings | 
                                                550,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,349,371,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                14,446,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                269,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                312,814,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                447,366,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,527,020,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,780,919,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Long-term borrowings | 
                                                1,499,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                723,476,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit liability | 
                                                490,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                331,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                30,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,919,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                615,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                1,598,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                817,926,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                3,125,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,598,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                6,633,604,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,633,604,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                4,652,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,652,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                -4,898,021,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,672,351,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -43,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -43,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                6,388,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,613,864,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                2,656,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,318,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                6,390,851,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,616,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                9,516,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,215,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |