The story takes place in a fantasy world where humans have been suffering from the attacks of the demon-like Vandels. Humans can fight back by becoming a Vandel Buster, a paid monster and Vandel assassin. The protagonist of the story, Beet, is a young boy who becomes a Vandel Buster to be like his heroes, the Zenon Warriors.

Koyuki Tanaka's boring life is changed after meeting Ryusuke Minami, a local musician with a bad attitude, who introduces him to foreign music.