Kusakabe Maron appears as an ordinary high‑school girl, yet she is the reincarnation of Jeanne d'Arc. With the help of the angel Fin Fish, she takes on the role of the night‑time thief Jeanne, traveling to seal demons that are trapped inside pieces of artwork. These demons prey upon the weak hearts of their owners, and when Maron frees them, the artworks vanish, an event that leads people to brand her a thief. The arrival of a new neighbor and classmate, along with a rival thief named Sinbad, complicates her nightly duties. Maron's best friend, the detective’s daughter, is determined to capture her, making her job anything but easy.