Some time during her childhood, Naru's father departed the family due to unknown circumstances. After living together with her mother for some time, Naru's mother encountered another man and fell in love with him. The man also had a daughter of his own and following their parents' marriage, Naru and the girl, Mei, became stepsisters.
While Mei had always wanted an elder sister to play with, Naru was unhappy and felt that her mother's love for her had transferred to the man and his daughter. With this in mind, Naru eventually moved to live in the Hinata Apartments.
- Due to her appearance in Negima! Magister Negi Magi, Mei and her father's original surnames may have been "Sakura".