Characters

The main heroine of the story is Amu Hinamori, a popular girl who is actually insecure. Peach-Pit uses Amu to explore differences between one's true self and the self that is presented to others. Like Jun Sakurada in Peach-Pit's previous work, Rozen Maiden, Amu tackles issues such as alienation and fitting in at school. Unlike most heroines in other magical girl series, Amu is neither the perfect sweetheart nor a complete klutz. Amu gets grumpy and frequently talks back to others in contrast to the polite schoolgirls that fill the genre.
Amu's Guardian Characters—Ran, Miki, Su, and Diamond—aid her in her quest of self-discovery. Each Guardian Character represents an aspect of Amu's true self. Ran represents Amu's desire to be more honest and athletic, Miki represents Amu's desire to be more level headed and artistic, Su represents Amu's desire to be more caring and improve her domestic skills, while Diamond represents Amu's desire to shine in front of others and be a good speaker and singer. Moreover, the Character Guardians are more than mere mascots who help Amu learn about her true self. They can also perform a "Character Change" where Amu's personality is replaced by an entirely different one.
However, Amu is not the only one with Guardian Characters. Each of the Guardians—Tadase Hotori, Nadeshiko (Nagihiko) Fujisaki, Kukai Soma, and Yaya Yuiki—have their own Guardian Characters. Amu also encounters Ikuto Tsukiyomi and Utau Hoshina (her last name actually being Tsukiyomi), two siblings who also have Guardian Characters and are employed by the Easter Company to search for the Embryo. As the series continues, Utau and Ikuto become extremely close friends with Amu.
Eventually, Nadeshiko Fujisaki and Kukai Souma leave the Guardians and are replaced by Rima Mashiro and Kairi Sanjo respectively. Kairi later leaves and is replaced by Nagihiko Fujisaki, Nadeshiko's real identity, as the third Jack's chair, with his new Guardian Character, Rhythm. Later in the series, Nagihiko once again faces Temari, his former Guardian Character, before Rhythm.