Maron Kusakabe is the main protagonist of the series, a sixteen-year-old high school student who lives alone in an apartment because her parents work overseas and have largely lost contact with her. By day she appears as a cheerful, talented gymnast who excels in both academics and sports, but by night she transforms into Kaitou Jeanne, the reincarnation of Joan of Arc. With the guidance of the angel Finn Fish, Maron receives a divine mission to seal demons that have infiltrated objects of beauty, usually paintings, and are stealing the purity of human hearts. When Jeanne hits a demon with a special pushpin and shouts Checkmate, the demon is sealed into a chess piece and the artwork vanishes, causing the public to believe she is a phantom thief stealing the art.

Beneath her warm smile and outgoing demeanor, Maron is deeply lonely. Her parents left her at a young age, and she has grown up without knowing what it truly means to be loved or to love. This emotional void makes her fearful of being hurt and causes her to hide her vulnerabilities behind a strong front. Her primary motivation is to fulfill her duty as Jeanne and protect others, but as the story progresses her desire for genuine human connection becomes equally important. She eventually learns to open her heart and trust those around her.

Maron’s central role is that of the heroine who battles demons while juggling her normal school life, friendships, and the complications of a secret identity. Her closest friend is Miyako Todaiji, a neighbor and classmate whose father is a police detective hunting the phantom thief. Their friendship provides Maron with a sense of family she lacks at home. Her relationship with Chiaki Nagoya, a transfer student who initially seems like a flirt, evolves from hostility into deep romantic love. Chiaki is also the rival thief Sinbad, and he knows Maron’s secret; his encouragement helps her confront her emotional wounds. The angel Finn serves as both a mentor and a source of conflict, as Finn’s true nature as a fallen angel is later revealed, leading to a crisis that tests Maron’s faith and resolve.

Through the course of the narrative, Maron undergoes significant growth. She begins the series isolated and mistrustful, but her encounters with Chiaki, Miyako, and even the demon knight Noin force her to face her fears of abandonment and rejection. A pivotal moment occurs when she is sent back to medieval France and meets the original Joan of Arc, an experience that strengthens her resolve and grants her a new understanding of sacrifice. After Finn’s betrayal she loses her transformation powers temporarily, only to regain a more powerful form. In the manga, Maron eventually marries Chiaki and has a daughter named Natsuki, symbolizing her journey from a lonely girl to someone who builds a loving family.

Maron’s abilities as Kaitou Jeanne include the power to detect and seal demons using a blessed pushpin. Her training in gymnastics gives her exceptional agility, speed, and acrobatic skill, which she uses both in combat and during her nocturnal escapades. She also possesses a rosary that can be used defensively, and at different points she gains upgraded costumes and weapons that enhance her sealing powers. Her strategic thinking and intuition allow her to outwit demons and rivals alike, though her emotional struggles sometimes weaken her concentration. Ultimately, her greatest strength is her capacity to keep fighting for the people she cares about, even when faced with betrayal or despair.