Consolidated Statement Of Changes In Equity
| Concept | 
                                    
                                        2023-04-01 to 2023-09-30  | 
                            
                                
                                    
                                        As at 2023-09-30  | 
                            
                                
                                    
                                        As at 2023-03-31  | 
                            
                                
                                    
                                        2022-04-01 to 2022-09-30  | 
                            
                        
|---|---|---|---|---|
| Consolidated statement of changes in equity | ||||
| Statement of changes in equity | ||||
| Net assets | — | 
                                        
                                             
                                                8,035,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                7,715,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Changes during period | ||||
| Profit (loss) attributable to owners of parent | 
                                        
                                             
                                                320,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | 
                                        
                                             
                                                108,131,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             
                                        
                                     |