Key Financial Data Of Group
| Concept | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | 2023-07-01 to 2023-09-30 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2022-04-01 to 2022-09-30 | As at 2022-09-30 | 2022-07-01 to 2022-09-30 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Net sales | 
                                                3,257,843,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,584,391,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,001,857,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary profit (loss) | 
                                                295,051,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                430,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                192,657,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net assets | — | 
                                                10,666,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,365,732,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,068,985,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | — | 
                                                13,636,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,480,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,757,154,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | 
                                                17.42
                                                
                                             | — | 
                                                12.82
                                                
                                             | — | 
                                                23.70
                                                
                                             | 
                                                10.63
                                                
                                             | — | 
                                                3.78
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  |  | — | — | 
| Equity-to-asset ratio | — | 
                                                0.782
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.769
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.789
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                49,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                740,075,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                643,411,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                37,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -352,052,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -120,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -180,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -191,824,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -180,693,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                2,309,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,402,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,548,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |