Quarterly Balance Sheet
| Concept | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2023-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2022-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2021-06-30 | As at 2021-06-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Quarterly balance sheet | ||||||||||||||||||||||||||
| Balance sheet | ||||||||||||||||||||||||||
| Assets | ||||||||||||||||||||||||||
| Current assets | ||||||||||||||||||||||||||
| Cash and deposits | — | — | — | 
                                                1,899,346,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,623,400,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                380,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                315,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets | — | — | — | 
                                                2,225,041,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,883,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | ||||||||||||||||||||||||||
| Property, plant and equipment | — | — | — | 
                                                50,505,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                56,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Property, plant and equipment | ||||||||||||||||||||||||||
| Buildings | — | — | — | 
                                                56,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                56,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Tools, furniture and fixtures | — | — | — | 
                                                36,435,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                34,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | 
                                                -42,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                -34,025,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | — | — | — | 
                                                71,697,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                55,275,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | ||||||||||||||||||||||||||
| Deferred tax assets | — | — | — | 
                                                36,387,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                20,187,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                35,310,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                35,087,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | — | — | — | 
                                                122,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                112,198,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Assets | — | — | — | 
                                                2,347,244,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,995,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | ||||||||||||||||||||||||||
| Current liabilities | ||||||||||||||||||||||||||
| Income taxes payable | — | — | — | 
                                                112,382,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                43,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | 
                                                61,400,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                31,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities | — | — | — | 
                                                363,734,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                219,568,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | ||||||||||||||||||||||||||
| Long-term borrowings | — | — | — | 
                                                45,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                95,821,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Asset retirement obligations | — | — | — | 
                                                35,005,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                34,773,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | — | — | — | 
                                                80,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                130,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | — | — | — | 
                                                444,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                350,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | ||||||||||||||||||||||||||
| Shareholders' equity | ||||||||||||||||||||||||||
| Share capital | — | — | — | 
                                                285,924,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                285,924,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Capital surplus | — | — | — | 
                                                1,158,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,158,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | — | 
                                                446,681,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                201,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Treasury shares | — | — | — | 
                                                -180,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Shareholders' equity | — | — | — | 
                                                1,890,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,645,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Share acquisition rights | — | — | — | 
                                                12,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | 
                                                285,924,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                446,681,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,902,687,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,158,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                446,681,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -180,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,158,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,890,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                201,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,158,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                201,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,645,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                285,924,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,158,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,645,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,190,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,194,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                128,158,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                95,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                128,158,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,298,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                967,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                967,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | — | — | — | 
                                                2,347,244,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,995,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — |