Quarterly 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 | 
|---|---|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | 
                                                523,141,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -12,436,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -138,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -69,302,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Depreciation | 
                                                133,062,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                131,360,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in allowance for doubtful accounts | 
                                                -3,939,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -18,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividend income | 
                                                -29,475,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -51,790,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest expenses | 
                                                18,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                15,632,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Foreign exchange losses (gains) | 
                                                -459,542,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -23,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Loss (gain) on sale of property, plant and equipment | 
                                                -331,614,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,631,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in trade receivables | 
                                                304,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                195,017,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in inventories | 
                                                -64,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                436,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in trade payables | 
                                                195,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -353,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                -9,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,450,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Subtotal | 
                                                396,387,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                255,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                34,694,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                59,639,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -20,674,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -21,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -15,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -15,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                233,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                257,533,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | 
                                                -148,276,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -15,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of property, plant and equipment | 
                                                1,178,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                433,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                3,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                659,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                956,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                485,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||||
| Repayments of long-term borrowings | 
                                                -95,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -147,040,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Redemption of bonds | 
                                                -14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of treasury shares | 
                                                -804,460,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -19,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -317,662,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -39,708,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -1,772,526,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -119,426,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                -17,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                37,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                -600,552,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                661,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                1,620,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,121,417,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,459,762,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |