Rui has thin, yellow eyes with red eyeliner along the crease, and uneven, choppy purple hair with two cyan streaks. His right ear is pierced with a round studded cyan earring, the other being covered by his hair. His voice is gentle, though it becomes strained when he is excited or curious. His casual outfit consists of a loose pale blue shirt with long pale yellow sleeves, decorated with designs in blue and pale brown, and two yellow lines down the front. He also wears dark gray slacks.