Key Financial Data Of Reporting Company
| Concept | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 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 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||||||||
| Net sales | — | — | — | — | — | 
                                                61,980,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                67,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                65,264,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                70,466,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                59,023,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                66,778,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                65,798,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                72,308,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                65,697,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                71,200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                2,524,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,947,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,957,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,458,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,851,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,859,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,718,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,822,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,409,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | 
                                                2,627,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                2,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,777,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,484,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                16,490,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | — | 
                                                33,269,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                31,212,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                29,312,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,848,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                30,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,492,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,687,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                27,158,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                27,778,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                25,951,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | — | 
                                                55,247,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                51,228,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                51,749,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                51,901,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                46,819,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                54,082,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                49,317,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                52,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                49,733,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | — | 
                                                2,156.15
                                                
                                             | — | — | 
                                                2,050.40
                                                
                                             | — | — | 
                                                1,925.92
                                                
                                             | 
                                                2,064.46
                                                
                                             | — | — | — | 
                                                1,968.89
                                                
                                             | 
                                                1,806.96
                                                
                                             | 
                                                1,893.06
                                                
                                             | — | — | 
                                                1,754.07
                                                
                                             | — | 
                                                1,732.03
                                                
                                             | — | 
                                                1,639.12
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | 
                                                60.00
                                                
                                             | — | — | — | — | — | — | — | 
                                                60.00
                                                
                                             | — | — | — | 
                                                60.00
                                                
                                             | — | — | — | — | 
                                                60.00
                                                
                                             | — | — | 
                                                55.00
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — | — | — | — | — |  | — | — | — | — | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | 
                                                172.55
                                                
                                             | — | 
                                                131.99
                                                
                                             | — | — | — | — | — | 
                                                176.87
                                                
                                             | — | — | 
                                                142.34
                                                
                                             | 
                                                116.40
                                                
                                             | 
                                                135.12
                                                
                                             | — | — | — | 
                                                159.65
                                                
                                             | 
                                                192.18
                                                
                                             | — | 
                                                144.13
                                                
                                             | — | 
                                                174.70
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — |  | — |  | — | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | — | 
                                                0.594
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.609
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.566
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.560
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.577
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.587
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.542
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.551
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.518
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.522
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | 
                                                0.087
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.063
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.095
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.071
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.065
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.070
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.094
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.090
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.104
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | 
                                                11.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                15.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                12.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                7.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | 
                                                0.348
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.339
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.376
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.382
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | — | 
                                                7,065,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                560,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,035,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                10,451,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -4,659,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | — | 
                                                -3,626,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,088,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,661,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                577,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | — | 
                                                -2,256,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,203,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                502,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -4,754,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                583,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | — | 
                                                10,954,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                9,761,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,283,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,904,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,868,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                466
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                97
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                345
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                986
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                80
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                391
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                850
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                316
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                819
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                983
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                965
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                805
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                951
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                791
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                873
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                770
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | — | 
                                                1.633
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.294
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.415
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.928
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | — | — | — | 
                                                1.962
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.388
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.312
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.286
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.905
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |