Key Financial Data Of Reporting Company
| Concept | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-07-01 to 2023-12-31 | As at 2023-06-30 | 2022-07-01 to 2023-06-30 | 2022-07-01 to 2022-12-31 | As at 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||
| Business results of reporting company | ||||||||
| Net sales | — | — | 
                                                1,927,829,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,343,580,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,044,774,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary profit (loss) | — | — | 
                                                -4,032,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                50,864,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -121,053,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net assets | 
                                                2,187,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,234,272,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,158,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                6,139,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,243,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,206,670,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                18.32
                                                
                                             | 
                                                -5.59
                                                
                                             | — | 
                                                -8.81
                                                
                                             | 
                                                -23.67
                                                
                                             | — | 
                                                -11.69
                                                
                                             | 
| Diluted earnings per share | — | — |  | — |  |  | — | — | 
| Equity-to-asset ratio | 
                                                0.339
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.407
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.332
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                -671,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                570,553,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -596,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -32,872,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -272,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -121,924,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                702,023,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -188,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                676,659,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | 
                                                647,018,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                651,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                501,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |