Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | 2024-04-01 to 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 | — | 
                                                28,077,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,259,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,053,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,096,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                23,126,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                23,874,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,786,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,820,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                20,652,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                3,400,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,030,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,364,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,457,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,623,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,654,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,384,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,563,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,592,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,707,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | 
                                                2,171,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,698,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,854,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,747,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,931,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | 
                                                810,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                810,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                810,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                810,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                810,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | 
                                                4,776,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                4,776,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                4,776,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                4,776,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                4,776,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                27,830,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                27,029,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                26,151,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,519,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,557,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,917,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,651,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,188,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,979,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                20,701,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                40,469,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                39,289,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                36,984,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                35,921,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                33,375,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                34,014,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                32,354,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,583,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,645,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                30,045,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                6,717.31
                                                
                                             | — | 
                                                6,524.04
                                                
                                             | — | — | — | 
                                                6,170.69
                                                
                                             | 
                                                6,021.55
                                                
                                             | — | 
                                                5,562.04
                                                
                                             | 
                                                5,647.00
                                                
                                             | — | — | — | 
                                                5,351.57
                                                
                                             | 
                                                5,242.15
                                                
                                             | 
                                                4,958.91
                                                
                                             | — | — | 
                                                4,893.18
                                                
                                             | 
| Dividend paid per share | — | — | — | 
                                                175.00
                                                
                                             | 
                                                127.50
                                                
                                             | — | — | — | 
                                                122.50
                                                
                                             | — | — | — | 
                                                117.50
                                                
                                             | — | — | — | — | 
                                                110.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | 
                                                60.00
                                                
                                             | 
                                                52.50
                                                
                                             | — | — | — | 
                                                50.00
                                                
                                             | — | — | — | 
                                                47.50
                                                
                                             | — | — | — | — | 
                                                45.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | 
                                                576.66
                                                
                                             | — | 
                                                516.25
                                                
                                             | 
                                                400.80
                                                
                                             | 
                                                413.15
                                                
                                             | — | — | 
                                                438.01
                                                
                                             | — | — | 
                                                441.87
                                                
                                             | 
                                                412.89
                                                
                                             | 
                                                443.68
                                                
                                             | — | — | — | 
                                                454.22
                                                
                                             | 
                                                471.20
                                                
                                             | — | 
| Diluted earnings per share | — |  | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | 
                                                0.6877
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.6880
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.7071
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.7104
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.7058
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.7032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.7001
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.7025
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.6846
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.6890
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                0.0899
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0827
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0692
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0699
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0811
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0804
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0815
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0861
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.0969
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0997
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                7.23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.08
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.97
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.06
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.03
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                8.17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.87
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | 
                                                0.3390
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.3181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.2797
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.2846
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.2422
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                2,109,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                730,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,573,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                162,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,298,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -834,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -886,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -788,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,033,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -961,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -523,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -490,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -587,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                6,380,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,071,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,036,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,885,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,005,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                556
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                491
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                532
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                470
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                478
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                535
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                523
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                471
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                505
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                457
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                124
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                116
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                108
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                104
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                101
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                106
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                112
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                119
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                108
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | 
                                                2.296
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                2.130
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.652
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.687
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.819
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | 
                                                2.337
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                2.443
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.671
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.539
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.599
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |