Statement Of Cash Flows
| Concept | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2022-01-01 to 2022-12-31 | As at 2022-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|
| Statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                456,310,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -362,909,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                16,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -1,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -580,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                454,425,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -363,482,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from operating activities | |||||
| Cash flows from operating activities | |||||
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -9,803,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -29,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -11,099,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -32,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from facilities maintenance and investing activities | |||||
| Cash flows from financing activities | |||||
| Proceeds from issuance of shares | 
                                                1,496,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,544,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                1,486,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,544,285,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                -90,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -90,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                1,929,560,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,148,065,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                3,266,408,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,336,847,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                188,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |