Rio Kitagawa

A tall and very pretty girl who constantly teases Mika-sensei, as she finds her various moods cute. She is a lesbian and has stated on several occasion that she loves small girls, thus making it no surprise that she has a (slightly sadistic) crush on Mika-sensei. She is constantly flirting with her, which often borders on molestation. She has an excellent body, which Kobayashi is jealous of. She also does well academically, though she isn't above failing a test on purpose if it means she'll get to spend time with Mika-sensei.

(Source: Wikipedia)