The Hundred Line: Last Defense Academy

Takumi Sumino is a thoroughly ordinary teenager living in the Tokyo Residential Complex, a place where every day blurs into the next and nothing bad ever seems to happen. That changes when monstrous creatures descend on the town and begin tearing it apart. A strange being calling itself Sirei appears and offers Takumi the power to protect the people he loves — all he has to do is stab himself in the chest. The next thing he knows, Takumi is at Last Defense Academy, a remote school ringed by a wall of otherworldly flames. Along with 14 other students, he's been conscripted into the Special Defense Unit, charged with keeping the school safe for the next 100 days. How much will they sacrifice to win back their ordinary lives and save the world from the grotesque invaders? So begins 100 days of war and despair.