The Rook, named after the Rook tattoo on his hand, is the human form of the Lion Fangire and a member of the Checkmate Four. The Rook is the one who slaughtered nearly the entire Wolfen Race and attacked both Ageha and Tsurara. Being one annoyed with boredom, the Rook devised his own personal game: the "Time Play". In a Time Play, he feeds on a select group of people within a time limit, with failure to make the intended number resulting in self-punishment with an electric shock strong enough to kill a human. However if he manages to succeed the right amount of victims within his game, he rewards himself with ice cream.
By 2008, Rook made his debut on chapter 12 when he wandered into town for his constant Time Plays and targeted the Newspaper Club for it. He defeated both Moka-sama and Kiva in Emperor Form, leaving the vampire bitterly humiliated and the Fandiri needing the medical magic of Castle Doran. Later in the School Festival Arc, Rook had entered Yokai Academy under Bishop's orders and began hunting Succubus and Yuki-onna for a 'Double Time Play' and began targeting the girls and their mothers. A combined efforts from both Kamen Riders and their friends allowed them to defeat Rook once and for all.