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 | 
                                                5,634,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,301,846,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,236,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                434,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                802,975,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                373,676,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                5,940,135,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,473,537,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,107,188,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                14,916,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,259,172,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,463,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                60.25
                                                
                                             | — | — | 
                                                73.79
                                                
                                             | 
                                                25.15
                                                
                                             | — | 
| Diluted earnings per share | 
                                                59.46
                                                
                                             | — | — | 
                                                72.20
                                                
                                             | 
                                                24.65
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.393
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.583
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                561,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                509,834,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                160,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -3,634,222,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,663,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -416,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                4,511,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                101,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                757,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,240,702,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                802,343,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,355,784,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |