Key Financial Data Of Reporting Company
| 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 reporting company | ||||||||
| Business results of reporting company | ||||||||
| Net sales | 
                                                15,473,962,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                19,723,498,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,920,585,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                498,648,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                386,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                279,632,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                6,482,361,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,315,806,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,240,422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                9,497,115,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,903,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,325,265,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                22.06
                                                
                                             | — | 
                                                7.25
                                                
                                             | — | 
                                                15.18
                                                
                                             | — | 
                                                9.80
                                                
                                             | 
                                                3.19
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.678
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.705
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.664
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |