Mei-chan is Naru's younger sister. Naru describes her as her "half-sister" in manga volumes 11 and 14. On the other hand, in the anime, episode 22, Mei said "My father married her mother." This leads some to speculate that they are step-sisters, although this is never confirmed. She initially tries to get Keitaro and Mutsumi together in the hopes that Naru would return home if Keitaro were taken. She gives up on this when she and Naru clear up a few family misconceptions. Also, in Love Hina Again, she makes a very brief appearance to help all the Hinata residents about Keitaro and Naru's relationship & help speed it up. She also appears in the last volume of the manga, seen standing off on the side with the rest of the residence of Hinata Inn while Naru is chasing Keitaro down after accidentally undressing her. She also plays a minor role in the Spring Movie.

The character of Mei-chan was created for and appears primarily in the Love Hina anime, though she is referred to in at least two places in the manga and is seen in the last chapter of the final volume of the manga.