Shareholdings
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 
|---|---|---|---|---|---|---|
| Shareholdings | ||||||
| Reporting company | ||||||
| Details of specified investment shares held for purposes other than pure investment | ||||||
| Issue | 
                                                ㈱ユーグレナ
                                                
                                             | 
                                                日揮ホールディングス㈱
                                                
                                             | 
                                                東洋エンジニアリング㈱
                                                
                                             | — | — | — | 
| Number of shares | 
                                                260,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                1,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                260,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                1,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Carrying amount | 
                                                131,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                157,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Purpose of shareholding, overview of business alliance, quantitative effects of shareholding and reason for increase in number of shares | 
                                                取引関係強化のため
                                                
                                             | 
                                                参考情報取得のため
                                                
                                             | 
                                                参考情報取得のため
                                                
                                             | — | — | — | 
| Whether issuer of aforementioned shares holds reporting company's shares | 
                                                無
                                                
                                             | 
                                                有
                                                
                                             | 
                                                有
                                                
                                             | — | — | — |