Tōko Natori is a 15-year-old female student at the Eastern Private Defense Academy's Fuji Training Facility in Japan. She has black hair, grey eyes, blood type A, and stands 1.58 meters tall. As class representative of her third-year cohort, she assumes leadership of the surviving students after a lethal assault by the mercenary group Trident during their summer training in August 2026. Though her initial appointment sparked rumors of nepotism, she consistently demonstrates capable leadership, earning her peers' trust. Her decisive and authoritative demeanor earns her the nickname "The Thoroughbred."

During the attack, which claims the lives of numerous students, instructor Kimiko Kamiya, and scientist Tomonori Takizawa, Tōko is entrusted with safeguarding the Regeneratable Artificial Nerve (RAN) experiment, deemed vital for Japan's future. This responsibility forces her and seven surviving classmates into a fugitive existence, branded terrorists by the public while evading both Trident and law enforcement. She spearheads the group's strategic decisions, including fortifying defensive positions, coordinating tactical retreats, and commandeering a civilian vehicle for escape. Her leadership extends to managing combat operations, such as rigging entry points with M18 Claymore mines and directing teammates during firefights.

In a documented engagement against the adversarial Wolverines, Tōko wields a Heckler & Koch USP .45 semi-automatic pistol. After witnessing multiple teammates' deaths, she intervenes to eliminate the last surviving Wolverine, Erica Mason, with precise gunfire. This action underscores her role as the group's tactical anchor and her willingness to engage directly in life-or-death situations. Her development centers on adapting to relentless combat, maintaining unit cohesion amid persecution, and balancing the weight of protecting the RAN experiment with ensuring her team's survival.