Maid-san to Ookina Ken

Makito lives an ordinary life with ordinary parents. But one day his father tells him that his family is a "Zaibatsu", a large family that controls banking and industrial companies. His father thinks that Kazuki has grown up enough to tell the secret and tells him to live at the main house by himself for a while to prepare for taking over the "Zaibatsu". He doesn't want to live alone but his father gets several maids for him. He comes to the main house and meets the maids there. He is surprised to see them because all of them wear a sword with them to protect him.

(Source: ErogeShop)