Goshūshō-sao Ninoh school student trained in difficult hand-to-hand coe house with his older sister Ryōko, who is alerous mercenary mission One day, his sister sends Mayu and Mikihiro Tsukis, to live with him to help Mayu overcome her fear ofMayu and Shungo share the sas even worse, Reika Hōjō, the student-council chair, is black their maid due to a video that Ryoko recorded, in which she tries to seduce Shungo