Quarterly Balance Sheet
| Concept | As at 2024-03-31 | As at 2023-12-31 | 
|---|---|---|
| Quarterly balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                1,623,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,720,720,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                10,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                19,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,440,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                1,665,575,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,785,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                170,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                181,547,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Tools, furniture and fixtures | — | — | 
| Tools, furniture and fixtures, net | 
                                                2,193,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,298,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                85,237,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                85,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Distressed receivables | 
                                                2,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Long-term prepaid expenses | 
                                                45,261,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,714,000
                                                
                                                    
                                                        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 | 
                                                255,941,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                267,237,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                1,921,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,052,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                3,131,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                3,569,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                37,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                99,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Asset retirement obligations | 
                                                22,674,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                27,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                65,555,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                127,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                876,352,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                847,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                1,944,946,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,916,098,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                -1,043,998,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -915,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                1,777,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,847,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation and translation adjustments | 
                                                8,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                70,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                66,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                1,855,961,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,924,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                1,921,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,052,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |