Key Financial Data Of Group
| Concept | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 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 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||||
| Operating revenue | — | — | — | — | — | — | — | 
                                                9,635,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,469,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,320,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,966,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,115,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary income | — | — | 
                                                194,646,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                182,058,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                148,759,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                135,711,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                143,132,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                41,112,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,537,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,506,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,868,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,444,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                25,048,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,271,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,635,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                29,349,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                21,203,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                17,768,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                15,144,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                10,795,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                -11,612,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                94,399,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -10,643,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -12,338,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                52,748,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                478,870,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                320,326,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                499,902,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                321,160,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                323,632,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                415,949,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                434,031,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                323,227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                454,371,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                321,933,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                10,977,796,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                324,235,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,138,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                325,444,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                325,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,518,089,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,670,473,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                324,519,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,706,729,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                322,242,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                5,487.84
                                                
                                             | — | — | — | — | 
                                                3,670.97
                                                
                                             | — | — | — | 
                                                5,706.68
                                                
                                             | 
                                                3,666.38
                                                
                                             | — | 
                                                3,601.31
                                                
                                             | 
                                                4,628.60
                                                
                                             | — | — | — | 
                                                4,724.15
                                                
                                             | 
                                                3,559.49
                                                
                                             | 
                                                4,760.75
                                                
                                             | — | — | 
                                                3,514.14
                                                
                                             | 
| Basic earnings (loss) per share | — | — | 
                                                335.91
                                                
                                             | — | — | — | — | 
                                                98.17
                                                
                                             | 
                                                89.47
                                                
                                             | 
                                                237.35
                                                
                                             | — | — | 
                                                81.59
                                                
                                             | — | — | 
                                                195.89
                                                
                                             | 
                                                90.99
                                                
                                             | 
                                                166.20
                                                
                                             | — | — | — | 
                                                60.89
                                                
                                             | 
                                                118.14
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — | — | — | — |  |  |  | — | — |  | — | — |  | 
                                                90.77
                                                
                                             | 
                                                165.79
                                                
                                             | — | — | — | 
                                                60.56
                                                
                                             | 
                                                117.50
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.0436
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.9879
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0448
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.9868
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.9957
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0395
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0402
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.9960
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0448
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.9968
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.0599
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.0267
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0247
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0463
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0228
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0420
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0257
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0350
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0173
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0262
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                9.39
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                32.13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                24.92
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.39
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                17.70
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.37
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.76
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.53
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                21.43
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.04
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                -255,788,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                294,419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -338,479,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                797,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                903,597,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                186,554,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -90,170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -380,777,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -85,510,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -78,519,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -9,431,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -10,509,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -8,049,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -8,942,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -5,495,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,145,045,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,223,711,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,029,972,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,757,277,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,054,043,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                202
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,504
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                305
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,935
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                3,549
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,463
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                3,591
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,774
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                571
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                521
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                626
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                669
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                724
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,186
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |