Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 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 | — | — | 
                                                13,940,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,210,021,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,678,773,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,861,882,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,545,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,310,068,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,744,841,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,652,770,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,797,169,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                43,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                308,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                543,475,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                302,399,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                495,811,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                293,825,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                582,586,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                583,836,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                547,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | 
                                                100,284,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -574,415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                363,039,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                405,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                419,757,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Equity in earnings (losses) of affiliates if equity method is applied | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | 
                                                754,096,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                748,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                742,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                736,752,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                726,984,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | 
                                                5,937,952
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,868,235
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                5,806,800
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,691,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                5,610,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | 
                                                2,363,072,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,472,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,447,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,357,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,825,414,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,198,461,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,407,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,451,838,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,027,078,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                8,609,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,302,164,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                7,421,698,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,852,825,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,867,334,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,598,008,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,926,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,591,755,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,431,542,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                398.08
                                                
                                             | — | 
                                                416.49
                                                
                                             | — | — | — | — | 
                                                417.48
                                                
                                             | 
                                                402.26
                                                
                                             | — | 
                                                487.00
                                                
                                             | 
                                                378.93
                                                
                                             | — | — | — | 
                                                423.08
                                                
                                             | 
                                                430.83
                                                
                                             |  | — | — | 
                                                361.33
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — |  |  | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — | 
| Interim dividend paid per share | — | — | — | — | — |  |  | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — | 
| Basic earnings (loss) per share | — | — | 
                                                -16.61
                                                
                                             | — | — | 
                                                16.98
                                                
                                             | 
                                                -98.37
                                                
                                             | 
                                                44.35
                                                
                                             | — | — | 
                                                63.09
                                                
                                             | — | — | 
                                                -38.20
                                                
                                             | 
                                                71.87
                                                
                                             | 
                                                64.05
                                                
                                             | — | — | — | 
                                                86.21
                                                
                                             |  | — | 
| Diluted earnings per share | — | — |  | — | — | 
                                                16.76
                                                
                                             |  | 
                                                43.33
                                                
                                             | — | — | 
                                                60.73
                                                
                                             | — | — |  | 
                                                67.63
                                                
                                             | 
                                                60.27
                                                
                                             | — | — | — | 
                                                79.83
                                                
                                             |  | — | 
| Equity-to-asset ratio | — | 
                                                0.274
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.297
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.330
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.344
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.411
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.333
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.348
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.372
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.457
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                -0.041
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.222
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.138
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                -0.095
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.150
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.381
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                23.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                14.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                22.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                48.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                65,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -609,174,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -344,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                399,818,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                668,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -486,289,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -356,305,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -650,342,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -925,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -25,623,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                1,220,322,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                376,176,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -429,204,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,890,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,103,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,932,258,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,132,912,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,698,159,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,122,019,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,757,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Number of employees | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                239
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                202
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                279
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                249
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                251
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                273
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                248
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                227
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                175
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                53
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                48
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                40
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                40
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                43
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                36
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | 
                                                0.095
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.164
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.223
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | 
                                                1.361
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.417
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.025
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.996
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |