Consolidated Statement Of Cash Flows
| Concept | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | 
                                                1,757,094,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,839,442,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,602,770,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,664,861,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation | — | 
                                                1,447,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,439,714,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Amortization of goodwill | — | 
                                                18,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                17,118,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in allowance for doubtful accounts | — | 
                                                -1,837,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -4,488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest expenses | — | 
                                                9,374,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,705,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in retirement benefit liability | — | 
                                                -1,613,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -38,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in provision for bonuses | — | 
                                                -369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,173,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Decrease (increase) in trade receivables | — | 
                                                151,242,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                50,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Subtotal | — | 
                                                3,227,002,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,572,738,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | — | 
                                                -497,203,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -610,253,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Decrease (increase) in inventories | — | 
                                                -701,969,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -435,960,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in trade payables | — | 
                                                185,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                89,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                2,722,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,957,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | — | 
                                                58,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -76,802,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest and dividends received | — | 
                                                1,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,095,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest paid | — | 
                                                -9,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -10,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Decrease (increase) in distressed receivables | — | 
                                                11,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,925,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | — | 
                                                -1,215,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -916,081,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -1,587,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,301,473,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of investment securities | — | 
                                                -3,410,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -3,299,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | — | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -14,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | |||||||
| Purchase of treasury shares | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -177,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Dividends paid | — | 
                                                -337,054,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -288,847,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Repayments of long-term borrowings | — | 
                                                -230,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -230,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -567,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -519,036,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Effect of exchange rate change on cash and cash equivalents | — | 
                                                10,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                29,187,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                578,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                166,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | 
                                                6,375,448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,797,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,630,624,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |