Tercio is one of the world's leading private security companies. Tsukasa, Shinrin, and Yasmin, who work there, are skilled bodyguards, but they are also high school girls. Danger looms over the three girls who are tasked with protecting a mysterious girl—!! A new kind of girls' action epic begins, a fusion of a story spun by Makoto Fukami of "PSYCHO-PASS" and the unparalleled artwork of Sakaki Yoshioka!!