Magical Girl Raising Project, Vol. 18 (light novel) — Asari Endou

Frederica, Old Blue, and Principal Halna clash over a powerful relic stored deep within the ruins hidden underneath the old school building. A murderous intruder picks off students one after another. Surrounded by enemies at every turn, Snow White stands before the entrance to the ruins that hold the fate of the world and makes a critical decision... At last, Snow White’s long saga comes to a close! How will the story of this girl at the mercy of destiny end…?