Extra Terrestrial Lifeform Evolto (地球外生命体・エボルト, Chikyūgai Seimeitai Eboruto) is the main antagonist of Kamen Rider Build. He is an alien who possessed Soichi Isurugi (石動 惣一 , Isurugi Sōichi) and caused the Sky Wall Tragedy. He transforms into Blood Stalk (ブラッドスターク, Buraddo Sutāku) and later Kamen Rider Evol (仮面ライダーエボル, Kamen Raidā Eboru).