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 | 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 | — | — | 
                                                88,330,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                75,299,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,348,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                75,579,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                56,243,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                67,493,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,147,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                65,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                56,407,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                69,044,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                6,974,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,893,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,776,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,142,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -448,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                598,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -613,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                562,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,342,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,476,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | 
                                                11,538,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,307,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,910,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                12,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,609,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | 
                                                24,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                24,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                24,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                24,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | 
                                                47,911,185
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                49,311,185
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                51,811,185
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                51,811,185
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                51,811,185
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | 
                                                210,126,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                197,028,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                221,136,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                208,601,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                185,679,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                194,814,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                202,180,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                193,674,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                219,953,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                214,708,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                244,059,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                224,488,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                260,929,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                241,966,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                207,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                221,200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                238,087,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                225,233,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                268,861,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                258,213,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                4,882.71
                                                
                                             | — | — | — | — | 
                                                4,602.94
                                                
                                             | — | — | — | — | 
                                                4,977.41
                                                
                                             | 
                                                4,718.91
                                                
                                             | — | 
                                                4,026.41
                                                
                                             | 
                                                4,204.64
                                                
                                             | — | — | — | 
                                                4,366.96
                                                
                                             | 
                                                4,199.74
                                                
                                             | 
                                                4,755.74
                                                
                                             | — | — | 
                                                4,655.84
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | 
                                                100.00
                                                
                                             | 
                                                82.00
                                                
                                             | — | — | — | 
                                                80.00
                                                
                                             | — | — | — | 
                                                56.00
                                                
                                             | — | — | — | — | 
                                                54.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | 
                                                45.00
                                                
                                             | 
                                                41.00
                                                
                                             | — | — | — | 
                                                40.00
                                                
                                             | — | — | — | 
                                                28.00
                                                
                                             | — | — | — | — | 
                                                27.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | 
                                                274.21
                                                
                                             | — | — | — | — | — | 
                                                264.51
                                                
                                             | 
                                                227.76
                                                
                                             | 
                                                246.61
                                                
                                             | — | — | 
                                                214.92
                                                
                                             | — | — | 
                                                228.31
                                                
                                             | 
                                                265.75
                                                
                                             | 
                                                280.20
                                                
                                             | — | — | — | 
                                                98.78
                                                
                                             | 
                                                113.25
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — | — | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.856
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.878
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.843
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.862
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.895
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.877
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.846
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.860
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.816
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.832
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.056
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.057
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.052
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.054
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.052
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.053
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.060
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.061
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.023
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.026
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                14.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                14.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                12.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                24.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | 
                                                0.378
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.360
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.372
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.211
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.547
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                6,521,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -1,677,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -6,679,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,533,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,542,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                4,952,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                8,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,001,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,776,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -9,329,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -9,325,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -10,006,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -3,420,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,756,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -4,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                48,158,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                45,887,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                48,884,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                53,004,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                43,447,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                74
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,778
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                39
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,301
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,301
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,301
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                364
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,779
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,333
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,359
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,795
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,828
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,399
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,863
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,442
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                202
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                136
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                136
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                136
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                202
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                138
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                135
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                198
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                182
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                122
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                166
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | 
                                                1.516
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.018
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.958
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.900
                                                
                                                    
                                                        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
                                                    
                                                
                                             |