Key Financial Data Of Reporting Company
| Concept | 2024-01-01 to 2024-06-30 | As at 2024-06-30 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-06-30 | As at 2023-06-30 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | 
                                                315,642,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,625,889,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                500,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -1,087,156,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,126,283,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -868,405,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                3,215,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,877,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,111,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                3,685,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,349,891,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,565,118,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                -63.25
                                                
                                             | — | 
                                                -68.62
                                                
                                             | — | 
                                                -53.81
                                                
                                             | — | 
| Diluted earnings per share |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.872
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.891
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.899
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                -222,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,677,464,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -938,544,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -7,108,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -11,376,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -6,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                279,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,182,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,222,158,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                3,026,030,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,889,101,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,684,625,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |