Key Financial Data Of Reporting Company
| Concept | 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 | 2024-04-01 to 2025-03-31 | As at 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 reporting company | |||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||
| Operating revenue | — | — | — | — | — | 
                                                5,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,191,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,766,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,590,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary income | — | 
                                                93,074,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                85,219,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                89,250,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                81,579,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                79,117,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                19,549,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,902,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,322,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,025,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,655,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,061,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,913,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,047,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,714,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | 
                                                3,842,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,249,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,651,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,894,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,909,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | 
                                                102,999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                102,999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                102,999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                102,999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                102,999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | 
                                                281,008,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                281,008,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                281,008,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                281,008,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                281,008,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                240,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                166,409,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                244,825,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                167,386,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                167,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                228,697,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                250,860,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                192,302,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                247,042,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                192,229,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                6,431,321,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                170,724,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                6,442,107,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                167,603,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                192,478,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,219,089,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,044,043,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                192,646,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,705,172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                193,747,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                852.98
                                                
                                             | — | — | — | 
                                                597.81
                                                
                                             | — | — | — | — | 
                                                863.54
                                                
                                             | 
                                                596.40
                                                
                                             | — | 
                                                596.17
                                                
                                             | 
                                                807.64
                                                
                                             | — | — | — | 
                                                795.45
                                                
                                             | 
                                                595.23
                                                
                                             | 
                                                782.13
                                                
                                             | — | — | 
                                                595.20
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | 
                                                15.50
                                                
                                             | — | 
                                                12.50
                                                
                                             | — | — | — | 
                                                10.00
                                                
                                             | — | — | — | 
                                                10.00
                                                
                                             | — | — | — | — | 
                                                7.50
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | 
                                                7.50
                                                
                                             | — | 
                                                6.25
                                                
                                             | — | — | — | 
                                                5.00
                                                
                                             | — | — | — | 
                                                3.75
                                                
                                             | — | — | — | — | 
                                                3.75
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | 
                                                47.28
                                                
                                             | — | — | — | 
                                                13.71
                                                
                                             | — | 
                                                11.58
                                                
                                             | 
                                                38.78
                                                
                                             | — | — | 
                                                13.02
                                                
                                             | — | — | 
                                                33.89
                                                
                                             | 
                                                7.65
                                                
                                             | 
                                                37.99
                                                
                                             | — | — | — | 
                                                7.69
                                                
                                             | 
                                                15.51
                                                
                                             | — | 
| Diluted earnings per share | — | 
                                                47.14
                                                
                                             | — | — | — | 
                                                13.67
                                                
                                             | — | 
                                                11.55
                                                
                                             | 
                                                38.68
                                                
                                             | — | — | 
                                                12.31
                                                
                                             | — | — | 
                                                32.05
                                                
                                             | 
                                                7.64
                                                
                                             | 
                                                34.07
                                                
                                             | — | — | — | 
                                                7.68
                                                
                                             | 
                                                15.24
                                                
                                             | — | 
| Equity-to-asset ratio | 
                                                0.0368
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.9736
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.0375
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.9978
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.8683
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0364
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0352
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.9977
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0364
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.9917
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                0.0552
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0230
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0194
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0464
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0203
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0400
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0150
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0462
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0215
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                9.20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                31.72
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                34.11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                17.81
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                6.84
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22.61
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4.55
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                23.14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | 
                                                1.1305
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.0794
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.7680
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.3071
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.9752
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                165,743,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                121,348,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,034,131,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                138,804,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                880,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -101,478,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -145,754,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                165,660,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -83,534,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -18,923,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -4,568,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -2,860,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -28,753,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,004,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,776,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                847,746,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                788,049,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                815,323,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,712,443,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,660,156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                2,252
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                275
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,939
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                2,326
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,397
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,562
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                1,405
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                58
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,331
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,347
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,333
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,309
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,285
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Total shareholder return | — | — | — | — | 
                                                3.0092
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2.6687
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.5920
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.1687
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.1380
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | 
                                                2.1343
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2.1679
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.5338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.4495
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.4213
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |