The story is set in August of 2026 at the Fuji Training Facility. Touko Natori, a third-year middle school student in the Eastern Private Defense Academy, is entrenched in field training with instructor Kamiya. It has been a harsh training regiment, but it is finally the last day. Kamiya proposes an extracurricular class under the name Newest Weapons Research. But then, an incident occurs that rocks all of Japan.