Key Financial Data Of Reporting Company
| Concept | 2024-10-01 to 2025-03-31 | As at 2025-03-31 | As at 2024-09-30 | 2023-10-01 to 2024-09-30 | 2023-10-01 to 2024-03-31 | As at 2024-03-31 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | 
                                                2,666,295,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,313,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,593,719,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                493,388,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                494,393,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                482,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                2,843,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,642,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,258,855,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                3,930,217,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,868,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,390,794,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                131.12
                                                
                                             | — | — | 
                                                150.50
                                                
                                             | 
                                                150.93
                                                
                                             | — | 
| Diluted earnings per share | 
                                                130.29
                                                
                                             | — | — | 
                                                150.30
                                                
                                             |  | — | 
| Equity-to-asset ratio | — | 
                                                0.723
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.683
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.666
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                93,355,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                639,424,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                538,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -11,404,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -36,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -18,792,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                -124,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                374,997,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,183,745,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,226,662,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,768,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |