Key Financial Data Of Group
| 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 group | ||||||||
| Business results of group | ||||||||
| Net sales | — | — | 
                                                5,018,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,586,030,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,957,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | — | 
                                                39,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,477,189,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,406,247,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                72,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,053,156,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,030,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income | — | — | 
                                                72,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,053,156,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,030,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | — | 
                                                6,398,256,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,401,948,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,379,317,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | — | 
                                                8,441,619,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,546,020,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,398,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | 
                                                1.68
                                                
                                             | — | 
                                                0.43
                                                
                                             | — | 
                                                6.21
                                                
                                             | 
                                                -0.14
                                                
                                             | — | 
                                                6.09
                                                
                                             | 
| Diluted earnings per share | — | — |  | — |  | — | — | 
                                                5.96
                                                
                                             | 
| Equity-to-asset ratio | — | 
                                                0.758
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.838
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.852
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                -2,729,636,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,732,794,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,302,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -109,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -230,349,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -67,826,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | — | 
                                                1,399,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -655,521,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -896,245,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | — | 
                                                1,147,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,586,486,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,077,549,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |