Major Shareholders
| Concept | 
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                                
                                    
                                        As at 2024-03-31  | 
                            
                        
|---|---|---|---|---|---|---|---|---|---|---|---|
| Major shareholders | |||||||||||
| Major shareholders | |||||||||||
| Name | 
                                        
                                             
                                                大水従業員持株会
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                農林中央金庫
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                大起産業株式会社
                                                
                                             
                                        
                                     | 
                                
                                    — | 
                                        
                                             
                                                利州株式会社
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                株式会社極洋
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                寳船冷蔵株式会社
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                水野 直明
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                中部水産株式会社
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                株式会社ニッスイ
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                ニチモウ株式会社
                                                
                                             
                                        
                                     | 
                                
                            
| Address | 
                                        
                                             
                                                大阪市福島区野田2-13-9
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                東京都千代田区大手町1-2-1
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                堺市北区中村町607-1
                                                
                                             
                                        
                                     | 
                                
                                    — | 
                                        
                                             
                                                大阪市福島区野田1-1-86
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                東京都港区赤坂3-3-5
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                大阪市西区南堀江3-15-14
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                大阪市天王寺区
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                名古屋市熱田区川並町2-22
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                東京都港区西新橋1-3-1
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                東京都品川区東品川2-2-20
                                                
                                             
                                        
                                     | 
                                
                            
| Number of shares held | 
                                        
                                             
                                                518,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                694,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                196,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                8,202,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                215,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                1,180,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                225,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                160,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                259,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                4,303,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                450,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Shareholding ratio (excluding treasury shares) | 
                                        
                                             
                                                0.0384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0514
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0145
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.6080
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0159
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0875
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0118
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0191
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.3190
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0333
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     |