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 | 
                                                9,291,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,039,908,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,938,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                674,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                512,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                171,417,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                431,625,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                510,882,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                58,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                442,179,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                600,909,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                74,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                9,093,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,180,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,653,486,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                13,165,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,354,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,167,821,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                33.02
                                                
                                             | — | 
                                                16.90
                                                
                                             | — | 
                                                37.26
                                                
                                             | — | 
                                                4.21
                                                
                                             | 
                                                8.81
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.691
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.687
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.657
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |