One day, Ryosuke Kaga, a high school boy attending Momozomo Academy (桃園学園, Momozomo Gakuen), meets a girl standing alone in the rain. Introducing herself as Lisara Restall, an elite Grim Reaper, she visited the human world in order to find "The Singular Man". Ryosuke makes a contract with Lisara, while sucking energy required for her activity in the human world from Ryosuke. The source of the energy is his lecherous spirit. To preserve his life, Ryosuke has no choice but to help in Lisara's search.
