Rei is a very handsome oni, he is unfortunately mainly interested in eating. He has the ability to transform into an "ushitora," a huge creature resembling a cross between a tiger and a bull. Rei has not yet learned to speak Japanese fully so he can only speak 1-5 words at a time in Japanese. When younger, Ran and Lum were both in love with him, but he became engaged to Lum, breaking Ran's heart and causing her to start to hate Lum. Lum eventually broke up with him, but he came to Earth to chase her and regain her love in which he became extremely jealous of Ataru and would transform when enraged.