Missy, known in Japan as 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, and if Sho won the Duel, which he does, he gets promoted to Ra Yellow. She lost to Sho's "Super Vehicroid Jumbo Drill", thereby missing out on the chance to go pro.

Source: Yu-Gi-Oh Wikia Entertainment