D.Gray-Man, Vol. 21 The Awakening of Alma Karma

A cursed teenage boy saves mankind one soul at a time.
Set in a fictional 19th century England, D.Gray-man is the story of Allen Walker, a 15-year-old boy who roams the earth in search of Innocence. Washed away to unknown parts of the world after The Great Flood, Innocence is the mysterious substance used to create weapons that obliterate demons known as akuma.
Allen has been dropped into a flashback of his surly colleague Yu Kanda's past, where a parade of disturbing secrets reveal themselves--including one that could at long last explain what makes Yu tick!