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 | 2024-04-01 to 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 | |||||||||||||||||||||||||
| Net sales | — | — | — | — | 
                                                37,289,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                35,664,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                35,507,623,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                35,831,912,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                32,624,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Operating revenue | — | — | — | — | — | — | — | 
                                                1,430,988,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,685,804,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,720,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,678,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,661,318,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                1,895,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                386,825,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                288,196,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,955,910,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                288,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,500,560,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                277,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,450,711,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                213,305,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -561,869,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | 
                                                647,560,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                538,172,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                444,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,907,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                193,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | 
                                                1,314,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,314,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,314,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,314,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,314,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | 
                                                1,645,360
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,645,360
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                1,645,360
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,645,360
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                1,645,360
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | 
                                                15,711,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,846,984,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                14,668,431,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,436,198,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,065,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,476,971,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                12,701,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,859,705,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,977,271,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,009,446,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                28,133,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,797,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                27,780,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,642,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,042,862,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,690,271,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                28,537,683,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,948,557,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,883,551,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                16,649,698,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                10,701.70
                                                
                                             | — | 
                                                3,337.45
                                                
                                             | — | — | — | — | — | 
                                                9,998.34
                                                
                                             | 
                                                3,054.51
                                                
                                             | — | 
                                                2,700.06
                                                
                                             | 
                                                9,186.82
                                                
                                             | — | — | — | 
                                                8,555.10
                                                
                                             | 
                                                2,622.20
                                                
                                             | 
                                                7,972.88
                                                
                                             | — | — | 
                                                4,040.30
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | 
                                                120.0
                                                
                                             | — | 
                                                160.0
                                                
                                             | — | — | — | 
                                                120.0
                                                
                                             | — | — | — | 
                                                120.0
                                                
                                             | — | — | — | — | 
                                                120.0
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | 
                                                60.0
                                                
                                             | — | 
                                                60.0
                                                
                                             | — | — | — | 
                                                60.0
                                                
                                             | — | — | — | 
                                                60.0
                                                
                                             | — | — | — | — | 
                                                60.0
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                863.97
                                                
                                             | — | — | 
                                                445.88
                                                
                                             | — | 
                                                370.55
                                                
                                             | 
                                                924.18
                                                
                                             | — | — | 
                                                304.69
                                                
                                             | — | — | 
                                                676.32
                                                
                                             | 
                                                -1,290.21
                                                
                                             | 
                                                657.79
                                                
                                             | — | — | — | 
                                                130.06
                                                
                                             | 
                                                -1,483.10
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — |  | — | — |  | — |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.552
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.411
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.523
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.381
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.289
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.482
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.441
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.258
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.397
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.361
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.083
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.140
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.127
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.096
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.113
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.076
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.080
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                3.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                5.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                26.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | 
                                                0.269
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.432
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.394
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.923
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | 
                                                1,485,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,588,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,769,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,745,852,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,556,358,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | 
                                                -492,203,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -583,063,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -561,282,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -443,560,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -711,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | 
                                                -1,037,119,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,491,616,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,439,974,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,501,094,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -875,105,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                1,369,452,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,413,649,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,899,577,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,130,979,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,329,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                795
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,031
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                178
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,057
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                34
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                43
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,080
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,112
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                291
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                90
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                378
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                381
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                386
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                403
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | 
                                                1.385
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1.438
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.319
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.287
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.252
                                                
                                                    
                                                        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
                                                    
                                                
                                             |