Manaka Sajyou is presumably the main antagonist of Fate/Prototype. She is the older sister of Ayaka Sajyou and the former Master of Saber in the Holy Grail War preceding the one held in the events of the story. She once again participates in the current Holy Grail War, acting as the Master of Beast and the six Servants besides Saber revived from the previous Holy Grail War.