Key Financial Data Of Group
| Concept | 2023-04-01 to 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | As at 2022-12-31 | 2022-04-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Net sales | 
                                                34,429,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                43,765,067,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,710,977,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                479,423,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -405,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,084,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                -27,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,553,427,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,784,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                669,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -754,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -586,178,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                9,340,666,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,711,181,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,870,935,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                35,995,736,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                36,903,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                35,510,034,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                -2.06
                                                
                                             | — | 
                                                -23.87
                                                
                                             | — | 
                                                -115.26
                                                
                                             | — | 
                                                -132.44
                                                
                                             | 
                                                -98.75
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.258
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.236
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.250
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |