Ran Kochou

Ran Kochou is an Obelisk Blue student infatuated with Marufuji Ryo to the point where she wears a locket with his picture in it. In the beginning of the second season, Ran Duels Ryo's younger brother, Sho, in hopes of pursuing her love interest in the Pro League.

(Source: Yu-Gi-Oh Wikia)