Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||||||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||||||||||||||
| Net sales | — | — | — | — | — | 
                                                253,136,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                224,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                197,084,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                221,920,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                169,116,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                190,865,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                173,544,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                193,189,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                168,879,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                190,067,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                23,071,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                21,282,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,266,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,624,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,247,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,656,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,817,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,784,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,196,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                16,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,430,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,830,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,952,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                6,266,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | — | 
                                                8,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                8,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | 
                                                54,661,156
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                56,661,156
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                58,161,156
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                59,661,156
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                59,661,156
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | 
                                                106,380,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                93,431,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                104,621,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                92,559,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                81,579,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                90,913,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                94,278,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                85,299,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                91,699,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                83,002,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | 
                                                200,839,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                185,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                202,161,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                187,491,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                157,705,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                172,305,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                183,609,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                171,310,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                171,313,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                159,141,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | 
                                                2,051.62
                                                
                                             | — | — | — | 
                                                1,801.49
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,967.03
                                                
                                             | 
                                                1,739.84
                                                
                                             | — | 
                                                1,494.89
                                                
                                             | 
                                                1,666.36
                                                
                                             | — | — | — | 
                                                1,685.20
                                                
                                             | 
                                                1,524.18
                                                
                                             | 
                                                1,611.76
                                                
                                             | — | — | 
                                                1,458.43
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                165.00
                                                
                                             | 
                                                85.00
                                                
                                             | — | — | — | 
                                                75.00
                                                
                                             | — | — | — | 
                                                85.00
                                                
                                             | — | — | — | — | 
                                                80.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                55.00
                                                
                                             | 
                                                35.00
                                                
                                             | — | — | — | 
                                                35.00
                                                
                                             | — | — | — | 
                                                35.00
                                                
                                             | — | — | — | — | 
                                                35.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | 
                                                326.31
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                313.83
                                                
                                             | 
                                                155.94
                                                
                                             | 
                                                165.58
                                                
                                             | — | — | 
                                                87.25
                                                
                                             | — | — | 
                                                85.80
                                                
                                             | 
                                                123.36
                                                
                                             | 
                                                115.13
                                                
                                             | — | — | — | 
                                                109.50
                                                
                                             | 
                                                103.12
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — | 
                                                325.32
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                312.88
                                                
                                             | 
                                                155.42
                                                
                                             | 
                                                165.02
                                                
                                             | — | — | 
                                                86.95
                                                
                                             | — | — | 
                                                85.50
                                                
                                             | 
                                                122.73
                                                
                                             | 
                                                114.55
                                                
                                             | — | — | — | 
                                                108.96
                                                
                                             | 
                                                102.60
                                                
                                             | — | 
| Equity-to-asset ratio | — | — | — | — | 
                                                0.529
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.503
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                0.517
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.493
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.516
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.526
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.512
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.496
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.534
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.520
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | 
                                                0.163
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                0.178
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.097
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.092
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.058
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.051
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.083
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.070
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.077
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.066
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | 
                                                10.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                10.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                16.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                17.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                13.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.526
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.545
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.860
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.689
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.731
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | 
                                                29,725,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,285,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -10,584,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                18,529,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -483,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | 
                                                1,897,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -969,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,384,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,423,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | 
                                                -11,398,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                -6,069,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -8,327,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -7,518,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -6,974,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | 
                                                43,848,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                23,500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                24,949,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                44,779,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                37,087,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                1,800
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                263
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,653
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,524
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,102
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                208
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                365
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                169
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                141
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                263
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,659
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,100
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2,073
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,627
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,607
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,096
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,548
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                2,048
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                380
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                298
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                372
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                357
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                493
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Total shareholder return | — | — | — | — | — | — | — | — | 
                                                3.192
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                2.033
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.407
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.291
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.266
                                                
                                                    
                                                        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
                                                    
                                                
                                             |