Goshuushou-sama Ninomiya-kun

High school student Shungo Ninomiya shares a huge home with his older sister Ryko, a hired gun. Ryko one day sends the Tsukimura siblings Mayu and Mikihiro to live with them. Mayu wants to harness her powers and get over her dread of men, but she is a young succubus, a creature that naturally draws attention from males. Mayu and Shungo are made to share a space, including the same bed, by Ryko and Mikihiro. Reika Hj, the head of the student council, who was envious of Shungo as a youngster, enters the household as a maid, further complicating matters.