Key Financial Data Of Group
| Concept | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | As at 2019-03-31 | 2018-04-01 to 2019-03-31 | 2018-04-01 to 2019-03-31 | As at 2019-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||
| Business results of group | ||||||||||||||||||||
| Net sales | 
                                                2,776,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,569,232,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,569,232,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                967,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                996,543,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                964,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,077,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,021,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -624,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -968,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -952,640,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -956,432,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -991,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,007,062,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,187,254,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -816,412,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -535,259,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,001,461,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -7,316,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -738,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -776,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -7,339,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                1,233,505,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,718,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,702,908,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,610,385,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,610,385,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,487,390,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,487,371,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,731,269,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                3,894,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,503,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,470,336,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,933,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,897,851,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,592,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,524,700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,151,358,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                32.36
                                                
                                             |  | — | — | — | 
                                                48.79
                                                
                                             | 
                                                48.30
                                                
                                             | 
                                                50.44
                                                
                                             | — | — | 
                                                50.44
                                                
                                             | — | 
                                                51.73
                                                
                                             | — | 
                                                51.73
                                                
                                             |  | — | — | 
                                                132.55
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                -20.77
                                                
                                             | — | — |  | 
                                                -17.86
                                                
                                             | 
                                                -17.35
                                                
                                             | — | — | — | 
                                                -34.79
                                                
                                             | 
                                                -34.79
                                                
                                             | — | 
                                                -264.65
                                                
                                             | — | 
                                                -264.65
                                                
                                             | — | — | 
                                                -43.84
                                                
                                             |  | — | 
| Diluted earnings per share |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.266
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.438
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.438
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.380
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.383
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.398
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.406
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.856
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                -1,421,259,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,169,561,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,267,471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,325,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -860,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -28,825,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                526,509,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -22,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -137,206,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -27,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                1,356,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                369,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                718,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,221,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                978,446,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                1,067,162,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,187,189,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,461,158,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,032,575,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,009,373,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Number of employees | — | 
                                                41
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                39
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                39
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |