Yui "Yui-nee" Kanakura

About

Yui is a childhood friend of Raku as well as his current homeroom teacher. She is also the head of the Chinese mafia group, Char Siu.


Yui also possesses a supposed key to Raku's locket, making her the fourth girl that Raku allegedly made a promise to when he was younger.
(Source: Nisekoi Wikia)