Abara

アバラ

On a ruined far-future Earth of colossal structures and decaying cities, a class of beings called Gaunas can grow weapons and armor out of bone-like matter. Kudou Denji is a Black Gauna who would rather be left alone, but a government organization presses him into hunting White Gaunas, people who mutate into ravenous monsters that tear through what is left of human settlements. Reluctantly drawn into the fight, Denji becomes the line between the survivors and the creatures hunting them.