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 | 
                                                9,211,502,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,919,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,103,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                313,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                268,023,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                148,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                238,585,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                289,827,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                195,677,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                216,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                341,992,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                49,298,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                6,137,558,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,016,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,728,041,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                15,060,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,944,091,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,789,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                175.60
                                                
                                             | — | 
                                                68.31
                                                
                                             | — | 
                                                213.28
                                                
                                             | — | 
                                                143.93
                                                
                                             | 
                                                99.17
                                                
                                             | 
| Diluted earnings per share | 
                                                172.23
                                                
                                             | — | — | — | 
                                                208.65
                                                
                                             | — | 
                                                140.81
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.344
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.366
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.353
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |