Key Financial Data Of Group
| Concept | 2024-04-01 to 2024-09-30 | As at 2024-09-30 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Net sales | 
                                                3,288,788,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,071,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,257,843,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                403,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                467,571,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                295,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                11,303,114,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,853,149,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,666,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                14,506,779,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,416,338,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,636,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                21.22
                                                
                                             | — | — | 
                                                25.68
                                                
                                             | 
                                                17.42
                                                
                                             | — | 
| Diluted earnings per share |  | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.779
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.753
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.782
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                316,412,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                414,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                49,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -241,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -42,315,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                -269,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -186,571,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -180,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,393,586,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,588,332,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,309,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |