Key Financial Data Of Group
| Concept | As at 2024-03-31 | As at 2024-03-31 | 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 | 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 | ||||||||||||||||||||||||
| Operating revenue | — | — | 
                                                10,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9,711,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,533,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,992,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,386,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Ordinary income | — | — | — | — | 
                                                222,551,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                214,368,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                187,630,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                180,896,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                172,140,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                7,365,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                38,438,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,234,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                35,597,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,997,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,656,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,073,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,682,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,454,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                27,033,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | — | 
                                                26,394,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                24,668,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                16,655,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                15,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                18,261,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | — | 
                                                71,869,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -14,029,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                68,705,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -20,805,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | — | — | 
                                                717,615,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                451,546,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                450,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                652,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                671,480,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                448,648,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                683,152,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                449,939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                619,754,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                448,151,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | 
                                                13,521,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                467,036,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                468,174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,181,457,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,169,219,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                469,020,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,204,020,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                462,775,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,079,796,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                459,129,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | 
                                                1,657.20
                                                
                                             | — | 
                                                1,043.77
                                                
                                             | — | 
                                                1,041.77
                                                
                                             | 
                                                1,506.25
                                                
                                             | — | — | — | 
                                                1,550.85
                                                
                                             | 
                                                1,037.06
                                                
                                             | 
                                                1,548.61
                                                
                                             | — | — | 
                                                1,022.79
                                                
                                             | — | 
                                                1,404.71
                                                
                                             | — | 
                                                1,018.73
                                                
                                             | 
| Basic earnings (loss) per share | — | — | 
                                                17.01
                                                
                                             | — | 
                                                61.01
                                                
                                             | — | — | — | 
                                                16.70
                                                
                                             | — | — | 
                                                57.02
                                                
                                             | 
                                                15.95
                                                
                                             | 
                                                38.06
                                                
                                             | — | — | — | 
                                                16.06
                                                
                                             | 
                                                34.12
                                                
                                             | — | 
                                                12.12
                                                
                                             | — | 
                                                40.70
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — |  | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | 
                                                0.053
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.966
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.962
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.049
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.047
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.956
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.055
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.972
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.055
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.976
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.016
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.038
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.016
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.015
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.024
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.015
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.023
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.012
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.028
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                67.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                18.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                28.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                8.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                29.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                34.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                10.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | 
                                                -153,188,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -1,632,540,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,834,219,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                794,763,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                195,306,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | 
                                                144,976,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                252,140,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -170,958,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -3,590,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -222,741,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | 
                                                -6,502,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -5,203,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -8,885,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -5,322,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -11,805,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | 
                                                2,209,694,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,224,398,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,609,985,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,955,589,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,169,723,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                70
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,978
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                444
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4,598
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                106
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                70
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                77
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,575
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                4,596
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                77
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,578
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                70
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4,561
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                584
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                103
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                702
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                743
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                799
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                815
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                819
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |