Key Financial Data Of Group
| Concept | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 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 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||||
| Ordinary profit (loss) | 
                                                -873,356,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,136,373,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,086,234,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,133,099,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,011,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,071,783,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,336,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,639,262,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,790,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,197,193,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                -1,288,138,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,118,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,571,541,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,561,636,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -2,238,558,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                -1,288,138,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,118,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,571,541,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,561,636,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -2,228,502,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | 
                                                353,666,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                353,666,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                574,812,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                855,169,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,980,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,698,410,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,076,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,649,689,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,728,481,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,286,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                867,275,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                507,227,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                949,263,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,511,438,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,685,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,116,549,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,368,102,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,894,992,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,088,076,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,616,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                1.28
                                                
                                             | — | — | 
                                                1.28
                                                
                                             | — | — | 
                                                2.58
                                                
                                             | 
                                                4.04
                                                
                                             | — | — | — | 
                                                9.84
                                                
                                             | 
                                                8.38
                                                
                                             | 
                                                16.96
                                                
                                             | — | — | 
                                                14.53
                                                
                                             | — | 
                                                25.81
                                                
                                             | — | 
                                                23.31
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                -4.74
                                                
                                             | — | 
                                                -6.05
                                                
                                             | — | — | — | — | — | 
                                                -5.80
                                                
                                             | — | — | 
                                                -5.81
                                                
                                             | 
                                                -12.94
                                                
                                             | 
                                                -13.72
                                                
                                             | — | — | — | 
                                                -8.77
                                                
                                             | 
                                                -8.86
                                                
                                             | — | 
                                                -12.13
                                                
                                             | — | 
                                                -13.73
                                                
                                             | — | 
| Diluted earnings per share |  | — |  | — | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.322
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.550
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.524
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.706
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.763
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.888
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.885
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.895
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.890
                                                
                                                    
                                                        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 | — | — | 
                                                -1,227,990,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -794,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,073,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,762,629,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -2,275,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -33,354,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -20,319,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -467,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -52,225,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -30,700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                671,365,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                95,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,478,967,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,164,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                527,656,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,117,635,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,836,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,899,092,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,713,947,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                54
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                36
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                66
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |