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 | 
                                                12,984,813,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                15,674,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,628,455,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                795,705,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                568,627,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                452,981,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                558,574,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                420,591,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                329,067,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                711,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                594,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                442,971,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                15,029,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,433,179,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,281,425,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                21,498,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                20,502,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                20,031,072,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                62.95
                                                
                                             | — | 
                                                17.98
                                                
                                             | — | 
                                                47.28
                                                
                                             | — | 
                                                36.96
                                                
                                             | 
                                                11.70
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.699
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.704
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.713
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |