Consolidated Statement Of Cash Flows
| Concept | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | 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 | |||||
| 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
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                956,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                485,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                3,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                659,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Purchase of treasury shares | 
                                                -804,460,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -19,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -317,662,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -39,708,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Redemption of bonds | 
                                                -14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | 
                                                -95,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -147,040,000
                                                
                                                    
                                                        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
                                                    
                                                
                                             |