Catholic schoolgirl Inaho discovers that a vampire, Mosquiton, is feeding off of her classmates. So she stakes him, but he is revived after her blood comes in contact with his remains. Mosquiton becomes her slave and also a history teacher. Together, along with Yuuki and Honou, the unlikely duo have many escapades and adventures. One of Inaho's main goals is to find the mythical O-Part to make some money!