Maron lives alone in an apartment on the same floor as Miyako and Chiaki. Her only companion in her home is a angel named Finn. Her parents live overseas and are rich. They design and create amusement parks, but they don't get along very well and are getting divorced. Because her parents are never around, Maron feels unloved. She finds herself falling in love with Chiaki, but because she has believed love doesn't exist, is a bit upset at herself for falling in love. Maron is best-friends with her neighbor, Miyako, and most of the time is a happy person.

Maron also has the power to transform in Kaitou Jeanne. As Kaitou Jeanne, Maron fights against the demon world and tries to stop the devil from destroy people and God. She can cure people who have been possessed by demons sent by the Devil that hide with paintings. She uses a small white pin which is thrown at the painting and the evil is locked inside. The pin then turns into a small chess piece which Finn collects. The painting then changes into an image of an angel.

The police are also after Kaitou Jeanne because they think that once the picture dispears, that she steals it. Miyako is the daughter of the detective in change of capturing Kaitou Jeanne, so she has decided that she will be the one person who will catch Kaitou Jeanne.