Kiritsugu is the main protagonist of the story. He is the Master of Saber, summoning her using Avalon, the holy sheath of Excalibur, as a catalyst. While a cynical and practical man, he wishes to find a way to end all conflict. Infamously known as the "Magus Killer" for his skills, he was hired by the Einzbern family to be their representative in the Fourth Holy Grail War. Believing that the Holy Grail could grant his wish for world peace, he decided to accept. An unconventional magus, Kiritsugu adopts a strategy of exploiting enemy magus' weak points using technology. His cynical views on life bring him into direct conflict with his Servant, and he has Irisviel appear in Fuyuki City as Saber's master in order to allow him to move more freely and to avoid contact with Saber as much as possible. He is the adoptive father of Shirou Emiya and the biological father of Illyasviel von Einzbern.