The story is set in August of 2026 at the Fuji Training Facility. Natori Touko, 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 a extracurricular class under the name Newest Weapons Research. But then, an incident occurs that rocks all of Japan.