Classmate to Meikyuu no Futekisetsu na Kouryakuhou takes place at Nishi High School, a school on the verge of closure with only seven students remaining and just two years left until its final graduation. One of those students, Hazakura Motoya, plans to quietly enjoy his remaining school life and coast toward graduation without trouble.

That peaceful routine is shattered when three mysterious transfer students — Kayama, Mizumura, and Toujou — suddenly enroll. Shockingly, these beautiful newcomers turn out to be members of a secret military division, hiding abilities far beyond those of ordinary students.

Soon after their arrival, an enormous and unexplained tower materializes directly on the school grounds, plunging Nishi High into chaos. Chosen by fate, Motoya is forced to team up with the three girls and enter the tower.

Inside awaits a deadly labyrinth filled with unknown threats, secrets, and trials. As classmates become battle partners, Motoya and the girls must rely on unconventional strategies to survive and uncover the truth behind the tower’s appearance.

Blending school life, action, fantasy, and mystery, Classmate to Meikyuu no Futekisetsu na Kouryakuhou delivers an unpredictable dungeon-exploration story where ordinary days collide with extraordinary danger.