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 | 
                                                12,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,146,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,335,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                242,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,206,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,074,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,218,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                420,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,157,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                13,070,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,710,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,492,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                30,573,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                28,961,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,506,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                31.30
                                                
                                             | — | 
                                                19.80
                                                
                                             | — | 
                                                -167.96
                                                
                                             | — | 
                                                -190.56
                                                
                                             | 
                                                -4.41
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.428
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.439
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.423
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |