Maron lives a double life that never stops demanding everything from her: sealing demons in artwork at night while maintaining a normal high school existence by day, all while being hunted as a criminal for stealing the very paintings she's saving. The show understands that being a magical girl isn't about power fantasies, it's about isolation, the exhaustion of lying to everyone you love, and the weight of a mission nobody else can see. Sinbad shows up as both rival thief and the one person who might actually understand what she carries, turning the entire second half into a question of whether she can let someone in without destroying them.

Maron leads a double life that would make any high school student's head spin. By day she looks like an ordinary high school girl, but she is really the reincarnation of Jeanne d'Arc. By night she becomes Jeanne, a phantom thief guided by an angel named Fin Fish. Her targets are demons hiding inside works of art, feeding on the weak hearts of the people who own them. Once she seals a demon, the artwork disappears, so the public sees her as nothing more than a thief. Things get harder when a new neighbor and classmate arrives, along with a rival thief called Sinbad. Her best friend, whose father is a detective, is also determined to catch her. The result is a mahou shoujo tale mixing action, comedy, mystery and romance.