Shiratori Yuto is the human host for Kamen Rider Yuuki in the Kamen Rider Den-O universe. He is introduced in the film 'Kamen Rider Den-O & Kiva: Climax Deka' as a supporting antagonist. Yuto is a mysterious young man whose body becomes possessed by an evil Imagin, granting him the ability to transform into Kamen Rider Yuuki. As Yuuki, he opposes the Den-O team, serving as a formidable adversary with his own agenda, adding tension and depth to the story.