He is the priest and regulator of the Holy Grail War during Fate Zero. He is also the father of Kirei Kotomine.
Risei Kotomine is created by Gen Urobuchi and designed by Takashi Takeuchi as one of the antagonists for the Fate Zero anime series. He originally appears in the visual Fate Zero, and makes his first anime debut in Fate Zero episode 1, Summoning the Ancient Heroes.
His Japanese voice actor is Hiroshi Masahi.