Major Shareholders
| Concept | 
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                                
                                    
                                        As at 2025-03-31  | 
                            
                        
|---|---|---|---|---|---|---|---|---|---|---|---|
| Major shareholders | |||||||||||
| Major shareholders | |||||||||||
| Name | 
                                        
                                             
                                                治山 公子
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                治山 美智子
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                有限会社岩渕コーポレーション
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                治山 高広
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                株式会社四国銀行
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                治山 純子
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                治山 邦雄
                                                
                                             
                                        
                                     | 
                                
                                    — | 
                                        
                                             
                                                株式会社はるか
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                はるやま社員持株会
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                岩渕 典子
                                                
                                             
                                        
                                     | 
                                
                            
| Address | 
                                        
                                             
                                                岡山県玉野市
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                岡山市中区
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                岡山市北区平和町1-1
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                埼玉県さいたま市大宮区
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                高知県高知市南はりまや町1-1-1
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                岡山市中区
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                岡山市中区
                                                
                                             
                                        
                                     | 
                                
                                    — | 
                                        
                                             
                                                岡山市北区平和町1-1
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                岡山市北区青江1-17-21
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                東京都杉並区
                                                
                                             
                                        
                                     | 
                                
                            
| Number of shares held | 
                                        
                                             
                                                720,082
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                406,792
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                1,324,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                331,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                699,940
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                318,700
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                1,383,322
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                9,262,886
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                3,336,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                392,350
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                349,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Shareholding ratio (excluding treasury shares) | 
                                        
                                             
                                                0.0449
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0254
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0827
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0206
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0437
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0199
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0864
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.5785
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.2083
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0245
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                0.0218
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     |