Key Financial Data Of Reporting Company
| Concept | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 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 | 
                                                13,309,481,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,936,064,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,266,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,674,769,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,687,595,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,092,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,287,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,321,971,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,431,632,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,726,039,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                596,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                989,719,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                232,261,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                568,627,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                565,403,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                718,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                727,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                810,618,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                543,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                586,597,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | 
                                                435,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                149,505,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                404,024,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                488,706,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                385,407,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | 
                                                9,000,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                9,000,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,066,872
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                10,066,872
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                10,066,872
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | 
                                                15,262,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,918,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,516,386,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,433,179,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,028,056,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,472,251,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,509,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,188,748,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,868,343,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,691,696,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | 
                                                21,659,301,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,038,991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                19,178,389,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,502,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                19,231,006,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,348,794,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,105,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                18,500,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                18,305,617,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,889,114,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | 
                                                1,720.08
                                                
                                             | 
                                                1,568.53
                                                
                                             | — | 
                                                1,523.27
                                                
                                             | 
                                                1,626.59
                                                
                                             | — | — | — | 
                                                1,554.65
                                                
                                             | 
                                                1,493.05
                                                
                                             | 
                                                1,497.13
                                                
                                             | — | — | 
                                                1,461.62
                                                
                                             | — | 
                                                1,426.12
                                                
                                             | — | 
                                                1,406.54
                                                
                                             | 
| Dividend paid per share | 
                                                22.00
                                                
                                             | — | — | — | 
                                                13.00
                                                
                                             | — | — | — | 
                                                13.00
                                                
                                             | — | — | — | — | 
                                                13.00
                                                
                                             | — | — | 
                                                13.00
                                                
                                             | — | — | — | 
| Interim dividend paid per share |  | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Basic earnings (loss) per share | 
                                                49.10
                                                
                                             | 
                                                79.40
                                                
                                             | — | — | 
                                                16.81
                                                
                                             | — | — | 
                                                47.28
                                                
                                             | 
                                                44.78
                                                
                                             | 
                                                60.85
                                                
                                             | — | — | — | 
                                                54.16
                                                
                                             | 
                                                63.14
                                                
                                             | — | 
                                                42.71
                                                
                                             | — | 
                                                46.92
                                                
                                             | — | 
| Diluted earnings per share |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | 
                                                0.705
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.695
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.704
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.704
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.729
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.734
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.707
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.713
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.703
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.709
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | 
                                                0.032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.047
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.011
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.029
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.030
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.040
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.038
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.043
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.031
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.033
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | 
                                                12.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                29.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                10.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                9.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | 
                                                0.448
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.773
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.290
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.240
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.304
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                1,274,204,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,129,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                434,839,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,190,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,015,168,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -193,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -496,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -590,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                230,004,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,696,342,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -135,291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -200,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -125,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -129,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -147,170,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | 
                                                5,634,863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,650,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,207,150,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,490,422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,182,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | — | — | 
                                                507
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                313
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                309
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                501
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                498
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                309
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                489
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                303
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                485
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                300
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | — | — | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | 
                                                1.579
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.235
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.194
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.267
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.900
                                                
                                                    
                                                        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
                                                    
                                                
                                             |