Quarterly Consolidated Balance Sheet
| Concept | As at 2024-06-30 | As at 2023-12-31 | 
|---|---|---|
| Quarterly consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                2,166,353,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,720,720,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                12,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                18,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,440,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                2,227,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,785,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                139,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                181,547,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | — | — | 
| Buildings and structures, net | 
                                                135,438,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                176,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles | — | — | 
| Machinery, equipment and vehicles, net | 
                                                2,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                164,909,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                85,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investment securities | 
                                                80,711,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,549,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,549,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -2,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                304,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                267,237,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                2,532,764,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,052,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                7,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                2,101,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                42,371,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                99,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Asset retirement obligations | 
                                                2,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                2,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                45,330,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                127,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                376,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                847,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                2,109,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,916,098,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                -41,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -915,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                2,445,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,847,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                -18,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                10,988,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                -7,985,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                50,381,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                66,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                2,487,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,924,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                2,532,764,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,052,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |