Yuya's best friend since they were kids. It's implied heavily throughout the show that she has romantic feeling for Yuya and that he returns those feelings.  She starts off as one of the best female leads we've had in a Yu-Gi-Oh! series, but does unfortunately succumb to the same outcome as most other female leads, and starts to become a damsel in distress. That still doesn't take away from her awesome presence in season 1, and I would like to do this character justice.