Consolidated Statement Of Cash Flows
| Concept | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | 
                                                2,295,156,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,326,448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,757,094,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,839,442,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Depreciation | 
                                                1,198,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,447,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Amortization of goodwill | 
                                                20,405,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                18,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in allowance for doubtful accounts | 
                                                -13,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,837,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest expenses | 
                                                11,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,374,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in provision for bonuses | 
                                                806,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in retirement benefit liability | 
                                                8,841,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,613,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Subtotal | 
                                                4,179,791,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,227,002,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in trade receivables | 
                                                -1,098,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                151,242,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -627,870,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -497,203,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in inventories | 
                                                -276,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -701,969,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in trade payables | 
                                                -5,422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                185,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                3,540,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,722,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                64,245,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                58,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                1,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -13,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -9,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in distressed receivables | 
                                                14,943,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | 
                                                -2,893,970,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,215,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -3,242,209,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,587,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of investment securities | 
                                                -3,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -3,410,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||||
| Proceeds from long-term borrowings | 
                                                2,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -384,970,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -337,054,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | 
                                                -280,013,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -230,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                1,335,016,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -567,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                25,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                1,658,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                578,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                8,033,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,375,448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,797,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |