A 12-year-old girl who dreams of becoming a pop singer, but who has a tumor in her vocal cords which restricts her ability to sing. She grew up in an orphanage, and then later went to live with her strict grandmother, Fuzuki, who forbade her from singing. When Mitsuki learns that she'll die if her vocal cords aren't removed, she refuses the surgery, saying she is more afraid of never singing again than she is of dying. With Takuto's help, she transforms into Fullmoon , a 16-year-old pop idol, completely free of cancer and able to sing. As Fullmoon, she is discovered by Seed Records during an audition, and in both the manga and anime she is depicted as releasing several hit singles. The anime ending theme songs are all supposedly sung by Fullmoon. Mitsuki chooses the stage name Fullmoon because mitsuki means "full moon" in Japanese, and because her childhood friend, Eichi Sakurai, wants to become an astronomer, and the name reminds her of him. Mitsuki decided to become a singer when she was ten years old, because she made a promise with Eichi that they would fulfill their dreams the next time they met.