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 | 
                                                11,681,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                17,024,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,931,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -24,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -393,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                -64,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -326,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                -45,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -315,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -236,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                5,111,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,157,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,236,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                8,503,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,659,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,834,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                -18.47
                                                
                                             | — | 
                                                33.73
                                                
                                             | — | 
                                                -93.43
                                                
                                             | — | 
                                                -73.16
                                                
                                             | 
                                                -40.51
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.6011
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.4838
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.5927
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |