Seraph of the End: Guren Ichinose, Resurrection at Nineteen, Volume 1

After the events of Seraph of the End: Catastrophe at Sixteen...

Guren Ichinose has committed a grievous sin--by bringing his friends back to life, he has violated the iron-clad taboo against human resurrection, and the Seraph of the End has brought the human race to its knees. The only survivors are demons and children, and those few who remain are threatened by rampaging monsters and callous vampires rounding up human beings like cattle. Faced with overwhelming despair, the survivors band together in hopes of reviving their world.
Tormented by the sin he has committed and unable to share the burden with his friends, Guren sets out on a new journey amid the ruins of the world he himself destroyed. But is he man or demon, savior or angel of death? Not even he knows for sure.