Key Financial Data Of Reporting Company
| Concept | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 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 | As at 2019-03-31 | 2018-04-01 to 2019-03-31 | 2018-04-01 to 2019-03-31 | As at 2019-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||||||||
| Net sales | — | — | — | 
                                                22,714,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                44,008,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,555,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,003,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,021,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                42,231,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,020,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                46,699,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                24,275,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                48,651,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | 
                                                1,268,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,902,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,329,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,055,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,852,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,138,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,817,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,804,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,119,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | 
                                                522,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                861,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,540,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                773,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,035,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | — | 
                                                7,789,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                7,780,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,407,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,055,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,034,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | 
                                                9,406,826
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                9,394,029
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                8,792,529
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                8,227,329
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                8,194,029
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | 
                                                23,506,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                33,086,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                32,049,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,700,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                28,500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,706,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                25,962,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                20,722,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                24,966,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                20,714,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | 
                                                45,544,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                61,838,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                64,546,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,645,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,906,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                49,654,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                61,242,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                46,527,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                60,609,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                47,165,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | 
                                                2,500.74
                                                
                                             | — | — | 
                                                3,322.62
                                                
                                             | — | — | — | — | 
                                                3,229.86
                                                
                                             | 
                                                2,524.85
                                                
                                             | 
                                                3,066.98
                                                
                                             | — | — | 
                                                2,584.31
                                                
                                             | — | 
                                                2,973.26
                                                
                                             | — | 
                                                2,520.36
                                                
                                             | 
                                                2,889.62
                                                
                                             | — | — | 
                                                2,530.02
                                                
                                             | 
| Dividend paid per share | — | — | — | 
                                                65.00
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                55.00
                                                
                                             | — | — | — | — | 
                                                40.00
                                                
                                             | — | — | 
                                                40.00
                                                
                                             | — | — | — | — | 
                                                40.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | 
                                                30.00
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                25.00
                                                
                                             | — | — | — | — |  | — | — |  | — | — | — | — |  | — | — | 
| Basic earnings (loss) per share | — | — | — | 
                                                55.66
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                35.37
                                                
                                             | 
                                                94.38
                                                
                                             | 
                                                211.49
                                                
                                             | — | — | — | 
                                                181.19
                                                
                                             | 
                                                282.98
                                                
                                             | — | 
                                                94.36
                                                
                                             | — | 
                                                212.57
                                                
                                             | — | — | 
                                                126.44
                                                
                                             | 
                                                219.95
                                                
                                             | — | 
| Diluted earnings per share | — | — | — |  | — | — | — | — | — | — | — | — |  | 
                                                94.20
                                                
                                             | 
                                                211.10
                                                
                                             | — | — | — |  |  | — | 
                                                94.27
                                                
                                             | — | 
                                                212.37
                                                
                                             | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | 
                                                0.516
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.505
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.470
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.497
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.422
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.457
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.399
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.445
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.390
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.439
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | 
                                                0.022
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                0.011
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.067
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.071
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.094
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.072
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.050
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.077
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | 
                                                23.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                37.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                7.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                10.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | 
                                                1.168
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                0.583
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.221
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.424
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.316
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,606,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,297,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,790,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,736,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,895,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -2,147,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,360,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,047,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -503,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,261,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -3,215,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -4,210,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,034,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -425,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,902,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | — | — | — | 
                                                9,821,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                10,838,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,402,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,710,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,955,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                265
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,534
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                137
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                166
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,229
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                524
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                193
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                157
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,322
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                156
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                3,589
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                494
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,574
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                476
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                3,597
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                468
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,529
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                444
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | 
                                                0.773
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                0.774
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.726
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.536
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.765
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | 
                                                1.162
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1.109
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.205
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.891
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.960
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |