Semi-Annual Balance Sheet
| Concept | As at 2024-06-30 | As at 2023-12-31 | 
|---|---|---|
| Semi-annual balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                1,103,656,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,325,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Inventories | 
                                                52,443,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                64,107,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                92,379,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                44,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                1,421,405,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,629,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Machinery and equipment | 
                                                233,509,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                233,509,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -232,930,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -232,343,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery and equipment, net | 
                                                579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Tools, furniture and fixtures | 
                                                82,364,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                85,451,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accumulated depreciation | 
                                                -82,364,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -85,451,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Tools, furniture and fixtures, net | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investments and other assets | 
                                                135,454,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                120,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Long-term prepaid expenses | 
                                                22,643,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                136,034,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                122,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                1,557,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,751,454,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Accounts payable - trade | 
                                                23,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                292,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                11,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Advances received | 
                                                9,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                432,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                539,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accounts payable - other | 
                                                63,872,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                116,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Non-current liabilities | 
                                                54,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                54,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                486,908,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                593,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other liabilities | — | — | 
| Provision for bonuses | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,730,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other liabilities | — | — | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                341,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,388,422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | ||
| Capital surplus | 
                                                1,281,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,988,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | ||
| Retained earnings | 
                                                -563,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -5,236,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -292,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                1,059,018,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,139,981,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                1,070,531,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,157,723,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share acquisition rights | 
                                                11,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,741,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                1,557,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,751,454,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |