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 | 
                                                19,103,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                43,146,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,892,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -1,900,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,700,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                743,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                -1,387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                646,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                -1,170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                479,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                803,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                32,211,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                33,884,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                34,186,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                72,389,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                71,387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                74,695,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                -143.55
                                                
                                             | — | 
                                                -76.67
                                                
                                             | — | 
                                                26.92
                                                
                                             | — | 
                                                66.87
                                                
                                             | 
                                                -70.71
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.441
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.471
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.453
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |