God divided happiness and misfortune into a man equally. However, there is only one person in the world who has only misfortune given to him. That person name is Takeshi, and he has only bad luck with his life since he was a kid.
Welcome Eru, a beautiful angel dispatched by god to "compensate" Takeshi losses and to protect him from his misfortune. At first, Takeshi is rather annoyed by Eru presence around him. But after Eru saves his life, finally Takeshi learns to accept Eru. Eru then uses her power to become human and lives with Takeshi along with his stepmother, Sanae, and his stepsister, Motoko.