Rui has yellow eyes and short, uneven purple hair with blue streaks. His right ear is pierced. Rui lives by his own set of rules, which causes people to consider him a weirdo. He's a literal genius. However, Rui often feels like an outcast for his inventions and his eccentric thinking. In WxS, Rui feels like he can be himself in the group and pushes himself to create better and better inventions.