Natsuo Sagan (奈津生 Natsuo) is the Sentouki (Fighter) of the Zero (Male) pair. He is one of Nagisa Sagan's experiments, and presumably the second generation of the Zero project . He is the Sentouki of Youji Sagan (who is also a Zero). Natsuo and Youji are infamous for their unwillingness to follow rules as well as their sadistic pleasure in witnessing people struggle and suffer. He makes his first appearance in Volume 2/Episode 6, when he and Youji attempt to rape Hitomi Shinonome. Upon nearing the attempt to rape Hitomi, Soubi Agatsuma thwarts their efforts and challenges them to a battle without the company of Ritsuka Aoyagi, his Sacrifice. Despite the pairs requests/recommendations for Soubi to contact his Sacrifice, he stubbornly refuses claiming he could defeat them without his Sacrific