Quarterly Consolidated Balance Sheet
| Concept | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | As at 2021-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Quarterly consolidated balance sheet | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Balance sheet | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assets | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current assets | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cash and deposits | — | — | 
                                                1,273,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,820,016,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,371,551,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,838,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Merchandise and finished goods | — | — | 
                                                227,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                398,519,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                211,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                356,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Work in process | — | — | 
                                                99,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                99,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                63,678,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                63,678,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Raw materials and supplies | — | — | 
                                                82,251,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                148,797,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                74,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                135,975,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | 
                                                196,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                140,837,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                250,400,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                205,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets | — | — | 
                                                2,785,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,576,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2,986,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,705,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property, plant and equipment | — | — | 
                                                1,846,756,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,859,270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,918,246,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,922,943,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Property, plant and equipment | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Buildings and structures | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,742,948,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,752,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -1,372,579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -1,340,558,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Buildings and structures, net | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                370,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                412,188,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Machinery, equipment and vehicles | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,151,105,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,100,030,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -981,579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -971,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Machinery, equipment and vehicles, net | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                169,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                128,080,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Land | — | — | 
                                                1,234,103,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,234,103,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,234,103,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,234,103,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Construction in progress | — | — | 
                                                28,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                28,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                111,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                111,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intangible assets | — | — | 
                                                73,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                73,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                74,836,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                74,842,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | — | — | 
                                                413,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                254,121,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                392,070,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                224,355,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment securities | — | — | 
                                                36,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                36,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                16,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                16,183,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | 
                                                65,880,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                217,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                67,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                208,172,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | — | — | 
                                                2,333,372,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,186,435,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2,385,153,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,222,141,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Assets | — | — | 
                                                5,118,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                5,762,579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                5,372,045,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,928,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current liabilities | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Notes and accounts payable - trade | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                199,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                282,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Short-term borrowings | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                27,503,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Income taxes payable | — | — | 
                                                10,986,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                13,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                42,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                42,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | 
                                                82,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                137,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                57,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                113,643,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities | — | — | 
                                                1,015,995,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,070,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,111,974,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,206,977,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Long-term borrowings | — | — | 
                                                81,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                81,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                142,046,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                142,046,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retirement benefit liability | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                250,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                229,741,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | 
                                                3,008,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,574,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                3,545,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,545,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | — | — | 
                                                548,220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                534,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                726,087,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                702,934,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | — | — | 
                                                1,564,216,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,604,408,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,838,061,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,909,912,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholders' equity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Share capital | — | — | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Capital surplus | — | — | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | 
                                                2,689,397,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,085,221,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                2,676,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,974,859,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Treasury shares | — | — | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Shareholders' equity | — | — | 
                                                3,545,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,941,297,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                3,532,293,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,830,935,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Valuation difference on available-for-sale securities | — | — | 
                                                9,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                9,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Foreign currency translation adjustment | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                207,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                185,506,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | — | — | 
                                                9,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                216,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                187,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | 
                                                3,941,297,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,554,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,085,221,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                207,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                715,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,545,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,399,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,659,047,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,158,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,689,397,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                216,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,676,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,533,984,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,532,293,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,018,132,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                730,346,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                187,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                185,506,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,974,859,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,830,935,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,399,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,631,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                50,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,410,461,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                748,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                48,681,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,399,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,408,941,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,650,941,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,701,142,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,794,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,552,866,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                468,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,489,881,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | — | — | 
                                                5,118,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                5,762,579,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                5,372,045,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,928,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |