Voiced by: Yuri Shiratori (Japanese), Rebecca Forstadt (English)

Mei Narusegawa (成瀬川 メイ, Narusegawa Mei) 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 stepsisters, 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 residents 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.

On a side note, in Negima, Ken Akamatsu's current manga, a character by the name of Mei Sakura shows up. This Mei looks identical to the Mei in Love Hina, leading many fans to believe that they may be the same person. As Mei's surname in Love Hina has never been actually confirmed as Narusegawa, this theory may prove to be true. Also, Mei of Love Hina wanted to study abroad, and the Mei of Negima was an exchange student in the U.S.

Source: Wikipedia