Key Financial Data Of Group
| Concept | As at 2024-06-30 | 2024-01-01 to 2024-06-30 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2023-06-30 | 2023-01-01 to 2023-06-30 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Net sales | — | 
                                                18,042,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                61,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                18,272,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | 
                                                -445,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -586,187,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -362,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                2,931,033,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,203,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,410,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                3,844,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,214,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,386,406,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                -56.15
                                                
                                             | 
                                                -75.42
                                                
                                             | — | — | 
                                                -46.73
                                                
                                             | 
| Diluted earnings per share | — |  |  | — | — |  | 
| Equity-to-asset ratio | 
                                                0.756
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.760
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.777
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                -371,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -562,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -315,940,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | 
                                                -7,821,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -19,474,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -11,347,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | 
                                                -108,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -53,418,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                2,385,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,873,773,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,056,601,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |