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 | 
                                                吉田 政功
                                                
                                             | 
                                                光通信㈱
                                                
                                             | 
                                                セフテック従業員持株会
                                                
                                             | — | 
                                                ㈱三菱UFJ銀行
                                                
                                             | 
                                                岡﨑 勇
                                                
                                             | 
                                                小川 由晃
                                                
                                             | 
                                                安本 雅洋
                                                
                                             | 
                                                柿沼 佑一
                                                
                                             | 
                                                ㈲裕﨑興産
                                                
                                             | 
                                                前山 満
                                                
                                             | 
| Address | 
                                                神奈川県横浜市磯子区
                                                
                                             | 
                                                東京都豊島区西池袋1-4-10
                                                
                                             | 
                                                東京都文京区本郷5-25-14
                                                
                                             | — | 
                                                東京都千代田区丸の内2-7-1
                                                
                                             | 
                                                東京都杉並区
                                                
                                             | 
                                                和歌山県和歌山市
                                                
                                             | 
                                                愛知県名古屋市瑞穂区
                                                
                                             | 
                                                埼玉県さいたま市中央区
                                                
                                             | 
                                                東京都文京区本郷5-25-14
                                                
                                             | 
                                                和歌山県和歌山市
                                                
                                             | 
| Number of shares held | 
                                                11,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                23,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                8,260
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                280,560
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                9,600
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                48,440
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                10,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                8,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                11,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                138,460
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                11,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Shareholding ratio (excluding treasury shares) | 
                                                0.0252
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0184
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.6254
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0214
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.1080
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0227
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0183
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0245
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.3086
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0250
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |