Ishida, a boy who lives by the motto: "Don't expect anything from people—just keep doing good deeds." Right after entering high school, Ishida meets a blonde beauty, Athena Fujisaki, whose beliefs are the complete opposite of his. She absolutely wants to help anyone in need—however, she is not a pure-hearted good person. She's a peculiar and dangerous girl who demands an equal return for every favor she does!