Taking place in the Fuji Training Facility in August 2026, the plot revolves around Natori Touko – a middle school student in her third year at the Eastern Private Defense Academy. Along with her instructor, Kamiya, Touko has endured a rigorous training regimen, which is now coming to an end. However, on the last day, Kamiya suggests an additional class – the Newest Weapons Research as an extracurricular activity. Nevertheless, Japan is shaken by a catastrophic event.