Quarterly Consolidated Statement Of Cash Flows
| Concept | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                273,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                533,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest and dividends received | 
                                                2,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,284,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | 
                                                -212,931,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -65,899,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                63,021,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                470,246,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -2,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -5,389,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Proceeds from sale of property, plant and equipment | 
                                                38,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Proceeds from sale of investment securities | 
                                                127,646,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | 
                                                474,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -61,779,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -55,042,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | |||||
| Proceeds from issuance of shares | 
                                                185,361,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                761,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of treasury shares | 
                                                -39,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Dividends paid | 
                                                -43,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -26,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                122,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                708,501,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                18,162,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -9,505,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                142,387,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,114,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                3,403,321,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,260,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,146,734,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |