Because of her mother's job, Chizuko Date has never stayed in one place for long or become attached to anything specific. However, while temporarily living with her grandfather Suikyou, she witnesses something extraordinary: a magical girl named Berry Blossom battling Chroma, a member of the evil organization Fossa Magna. Seeing Berry Blossom save the day sparks a passion in Chizuko, and she vows to become a fan of the new magical girl in town. As time goes on, Berry Blossom's popularity fades due to her opponent's incompetence. When Chizuko randomly runs into Chroma himself, she does not hold back her complaints against him. For his part, Chroma does not enjoy being defeated repeatedly; moreover, Fossa Magna will force him to resign if he continues to lose. In desperation, Chroma begs Chizuko to become his second-in-command and help him with his evil deeds. For the sake of Berry Blossom regaining the spotlight, Chizuko must question whether it is right to join forces with the magical girl's sworn enemy.