Akihisa Yoshii lands in Class F, the bottom rung of an academy that sorts students into tiered classrooms by entrance-exam scores, down to the furniture. When Class F challenges the elite Class A to reclaim better facilities, students summon beasts whose combat strength is drawn directly from their test scores, turning grades into a battlefield. Yoshii leads his scrappy, low-scoring friends into every summoning duel, among them Mizuki Himeji, a naturally brilliant student stuck in F only because illness cut her exam short.