Shareholdings
| Concept | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|
| Shareholdings | ||
| Reporting company | ||
| Details of specified investment shares held for purposes other than pure investment | ||
| Issue | 
                                                ENECHANGE株式会社
                                                
                                             | — | 
| Number of shares | 
                                                480,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                720,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Carrying amount | 
                                                496,800,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                675,360,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Whether issuer of aforementioned shares holds reporting company's shares | 
                                                無
                                                
                                             | — |