Consolidated Statement Of Cash Flows
| Concept | As at 2024-12-31 | 2024-01-01 to 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 | — | 
                                                694,653,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                613,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | — | 
                                                57,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | — | 
                                                -11,026,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -12,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | — | 
                                                -164,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -211,240,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                529,055,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                389,555,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | — | 
                                                -230,752,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -691,846,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of property, plant and equipment | — | 
                                                29,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,204,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -212,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -717,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Proceeds from issuance of shares | — | 
                                                12,400,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                34,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of treasury shares | — | 
                                                -29,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from long-term borrowings | — | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                550,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | — | 
                                                -256,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -255,347,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -200,489,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                325,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                116,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,317,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | 
                                                419,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                303,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                306,561,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |