Key Financial Data Of Reporting Company
| Concept | 2024-01-01 to 2024-03-31 | As at 2024-03-31 | 2023-10-01 to 2024-03-31 | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | 2023-01-01 to 2023-03-31 | As at 2023-03-31 | 2022-10-01 to 2023-03-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||
| Business results of reporting company | ||||||||
| Net sales | — | — | 
                                                8,359,164,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,792,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,497,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | — | 
                                                172,937,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                603,573,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                414,790,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | — | 
                                                2,118,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,034,153,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,903,625,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | — | 
                                                4,912,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,106,944,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,128,573,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | 
                                                4.32
                                                
                                             | — | 
                                                9.75
                                                
                                             | — | 
                                                44.53
                                                
                                             | 
                                                9.45
                                                
                                             | — | 
                                                30.94
                                                
                                             | 
| Diluted earnings per share | — | — | 
                                                9.75
                                                
                                             | — | 
                                                44.53
                                                
                                             | — | — | 
                                                30.94
                                                
                                             | 
| Equity-to-asset ratio | — | 
                                                0.399
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.368
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.344
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                -11,730,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                788,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                333,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -9,637,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -61,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -45,551,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -210,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -5,835,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | — | 
                                                2,524,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,745,680,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,510,804,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |