HUNDRED LINE: Saishuu Bouei Gakuen

Takumi Sumino is a perfectly average teenager living in the Tokyo Residential Complex, a place where every day is peaceful and nothing bad ever happens. His ordinary life is shattered when grotesque monsters attack the town, throwing everything into chaos. A mysterious creature named Sirei appears and offers him the power to protect those he cares about—but the price is that he must stab himself in the chest.

Takumi awakens in Last Defense Academy, a school isolated by a wall of otherworldly flames. He and fourteen other students have been forced into the Special Defense Unit, a team tasked with defending the school for the next one hundred days. As monstrous invaders threaten their lives, the students must decide how much they are willing to sacrifice to reclaim their normal lives and save the world.