Tsukasa Shishio (獅子王司 Shishiō Tsukasa) is the former primary antagonist of Dr. Stone. He was the antagonist of the first several arcs, his goal being to thin out the human population in order to create a new world without modern technology for the pure-hearted youth. Despite his claims that no threat would come after Senku and Taiju, which proved ironic,[11] Tsukasa became one of the biggest obstacles to Senku's Kingdom of Science and restoring humanity as a whole in general. In order to fight and prevent Senku from establishing a scientifically advanced civilization, he goes on to found his own society comprised of strong warriors to further his agenda. Eventually coming to a stalemate, he forms a temporary truce with Senku after the latter proposed to save his sister and, having reaffirmed his promise to never again let Senku be harmed, ultimately defeats the traitorous Hyoga along with him. After his life was saved by Senku by de-petrifying him from his cryogenic state, Tsukasa joins the Kingdom of Science and embarks with them on their trip to the United States, channeling his ideals differently - yet still striving for a morally pure world without exploitation of the innocent.