Kaoru Minaguchi is bad at school, bad at sports, has no talent worth naming and no girlfriend, which is exactly what brings Airi to his door. She is a shinigami who reaps 'no-lifers', and Kaoru only stays alive if he can turn himself into a 'real-lifer'. His plan is to send love letters to the only four girls he knows, and all four say yes. Now he has to keep four girlfriends at once without any of them finding out about the others, with Airi watching.