Key Financial Data Of Group
| Concept | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-04-01 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 | — | — | 
                                                4,984,281,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,584,391,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,687,568,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                389,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                430,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                325,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | 
                                                10,729,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,365,732,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,181,531,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | 
                                                13,825,776,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,480,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,959,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | 
                                                4.55
                                                
                                             | 
                                                21.97
                                                
                                             | — | 
                                                23.70
                                                
                                             | — | 
                                                18.91
                                                
                                             | 
                                                8.27
                                                
                                             | 
| Diluted earnings per share | — | — |  | — |  | — |  | — | 
| Equity-to-asset ratio | 
                                                0.776
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.769
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.786
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |