Ryousuke Kaga is a hopelessly romantic teenager who takes in a girl he finds standing alone in the rain, and gets a sword through the chest for his trouble. The girl is Lisara Restall, a Grim Reaper working undercover in the human world, and the contract she forces on him gives Ryousuke three months to live unless he helps her find the man she was sent to locate. Worse, her powers run on the lecherous energy she siphons out of him, which turns his ordinary school life into a daily obligation.