Key Financial Data Of Reporting Company
| Concept | 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 | 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 | 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 reporting company | |||||||||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||||||||
| Net sales | — | — | — | — | — | — | — | — | 
                                                69,557,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                63,694,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                61,980,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                67,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                65,264,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                70,466,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                59,023,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                66,778,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                65,798,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                72,308,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | — | — | — | 
                                                3,366,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,037,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,524,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,957,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,458,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,851,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,859,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,718,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,012,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,777,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,484,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | 
                                                34,675,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                32,161,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                33,269,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,212,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,312,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,848,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                30,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,492,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,687,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                27,158,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | 
                                                64,148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                60,362,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                55,247,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                51,228,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                51,749,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                51,901,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                46,819,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,082,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                49,317,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | 
                                                2,262.99
                                                
                                             | — | — | 
                                                2,126.83
                                                
                                             | — | — | — | — | 
                                                2,156.15
                                                
                                             | 
                                                2,050.40
                                                
                                             | — | 
                                                1,925.92
                                                
                                             | 
                                                2,064.46
                                                
                                             | — | — | — | 
                                                1,968.89
                                                
                                             | 
                                                1,806.96
                                                
                                             | 
                                                1,893.06
                                                
                                             | — | — | 
                                                1,754.07
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                60.00
                                                
                                             | 
                                                60.00
                                                
                                             | — | — | — | 
                                                60.00
                                                
                                             | — | — | — | 
                                                60.00
                                                
                                             | — | — | — | — | 
                                                60.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — |  |  | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | — | — | — | 
                                                145.26
                                                
                                             | — | — | — | 
                                                132.72
                                                
                                             | 
                                                172.55
                                                
                                             | 
                                                131.99
                                                
                                             | — | — | 
                                                176.87
                                                
                                             | — | — | 
                                                142.34
                                                
                                             | 
                                                116.40
                                                
                                             | 
                                                135.12
                                                
                                             | — | — | — | 
                                                159.65
                                                
                                             | 
                                                192.18
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — | — | — | — |  | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | 
                                                0.533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.594
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.609
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.566
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.560
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.577
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.587
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.542
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.551
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | — | — | — | 
                                                0.066
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.063
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.087
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.063
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.095
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.071
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.065
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.070
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.094
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | — | — | — | 
                                                15.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                16.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                9.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                12.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.452
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.348
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.339
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.376
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | — | — | 
                                                621,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                7,065,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                560,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,035,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                10,451,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | — | — | 
                                                -6,500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -3,626,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,088,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,661,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | — | — | 
                                                5,334,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -2,256,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,203,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                502,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -4,754,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | 
                                                10,379,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                10,954,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,761,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,283,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,904,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                339
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                391
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                468
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                302
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                992
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                845
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                986
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                850
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                819
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                983
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                965
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                805
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                951
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                791
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | 
                                                1.968
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.793
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.412
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.280
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.548
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | — | — | 
                                                2.134
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2.168
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.534
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.450
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.421
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |