Matou Kariya is a magus and Master in the Fourth Holy Grail War who becomes the Master of Berserker. He is the younger son of the Matou family who was disowned and returns to participate in the Holy Grail War. Kariya's primary motivation is to save his cousin Sakura from the cruelty of the Matou family, particularly from his father Zouken's control. Despite the immense burden of controlling Berserker, a Servant that consumes vast amounts of magical energy, Kariya endures the pain inflicted by the crest worms implanted in his body. He demonstrates his selflessness by ultimately sacrificing his Command Spells and his position as Berserker's Master to ensure Sakura's safety and escape from the Matou mansion.