Key Financial Data Of Group
| Concept | As at 2025-03-31 | 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 | 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 | ||||||||||||||||||||||||||
| Ordinary profit (loss) | — | — | — | 
                                                19,938,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                17,087,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,810,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,852,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,623,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,001,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,323,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,818,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,287,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | 
                                                11,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                15,602,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                7,917,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,279,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | 
                                                12,387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                25,597,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9,607,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,878,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                16,748,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | 
                                                156,486,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                115,842,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                151,562,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                114,856,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                103,151,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                131,992,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                130,788,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                103,110,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                126,311,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                100,794,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | 
                                                268,448,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                172,965,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                266,494,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                174,236,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                166,751,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                237,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                228,159,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                148,593,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                228,855,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                149,439,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | 
                                                2,282.91
                                                
                                             | — | — | — | — | 
                                                1,786.24
                                                
                                             | — | — | — | — | 
                                                2,194.04
                                                
                                             | 
                                                1,749.64
                                                
                                             | — | 
                                                1,553.42
                                                
                                             | 
                                                1,894.37
                                                
                                             | — | — | — | 
                                                1,829.27
                                                
                                             | 
                                                1,512.62
                                                
                                             | 
                                                1,776.35
                                                
                                             | — | — | 
                                                1,479.30
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | 
                                                169.44
                                                
                                             | — | — | — | — | — | 
                                                157.75
                                                
                                             | 
                                                206.05
                                                
                                             | 
                                                235.97
                                                
                                             | — | — | 
                                                126.63
                                                
                                             | — | — | 
                                                117.31
                                                
                                             | 
                                                112.34
                                                
                                             | 
                                                106.35
                                                
                                             | — | — | — | 
                                                99.34
                                                
                                             | 
                                                121.51
                                                
                                             | — | 
| Diluted earnings per share | — | — | — |  | — | — | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | 
                                                0.552
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.670
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.540
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.659
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.619
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.531
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.547
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.694
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.529
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.674
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | 
                                                0.076
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.089
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.125
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.116
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.083
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.063
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.075
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.059
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.070
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.072
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | 
                                                13.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                14.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                14.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                15.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                15.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | 
                                                -21,219,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                20,738,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                4,806,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -8,544,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                973,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | 
                                                -4,982,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                2,148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,748,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,071,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -6,913,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | 
                                                1,907,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -5,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -9,822,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,435,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | 
                                                42,013,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                63,265,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                43,946,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                48,791,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                50,670,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                1,468
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                189
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,267
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                256
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,282
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,727
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                266
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                5,031
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,654
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,611
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,890
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                5,079
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,555
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,544
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |