Shareholdings
| Concept | As at 2024-05-31 | As at 2024-05-31 | As at 2024-05-31 | As at 2023-05-31 | As at 2023-05-31 | As at 2023-05-31 | 
|---|---|---|---|---|---|---|
| Shareholdings | ||||||
| Reporting company | ||||||
| Details of specified investment shares held for purposes other than pure investment | ||||||
| Issue | 
                                                ㈱建設技術研究所
                                                
                                             | 
                                                野村ホールディングス㈱
                                                
                                             | 
                                                ㈱大和証券グループ本社
                                                
                                             | — | — | — | 
| Number of shares | 
                                                50,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                24,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                30,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                50,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                24,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                30,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Carrying amount | 
                                                254,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Purpose of shareholding, overview of business alliance, quantitative effects of shareholding and reason for increase in number of shares | 
                                                業界動向の把握、情報収集等を目的に継続して保有しております。
                                                
                                             | 
                                                当社グループの事業維持・拡大を支える安定的な金融取引をおこなうため、継続して保有しております。
                                                
                                             | 
                                                当社グループの事業維持・拡大を支える安定的な金融取引をおこなうため、継続して保有しております。
                                                
                                             | — | — | — | 
| Whether issuer of aforementioned shares holds reporting company's shares | 
                                                有
                                                
                                             | 
                                                無(注2)
                                                
                                             | 
                                                無(注2)
                                                
                                             | — | — | — |