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 | 
                                                11,168,227,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,293,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,290,786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                281,685,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                549,390,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                219,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | 
                                                155,147,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                312,889,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                105,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | 
                                                183,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                310,024,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                111,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                7,622,221,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,508,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,310,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                14,412,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,426,489,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,072,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                27.67
                                                
                                             | — | 
                                                14.54
                                                
                                             | — | 
                                                55.79
                                                
                                             | — | 
                                                18.86
                                                
                                             | 
                                                19.51
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.529
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.520
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.519
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |