D.gray-man (3-in-1 edition), volume 6: includes volumes 16, 17 & 18, paperback/katsura hoshino

Gray-man is the story of Allen Walker, who roams a fictional 19th century Earth in search of Innocence, a mysterious substance used to fight demons called akuma.

A mysterious virus has affected the Black Order, turning most among its ranks into zombiesAllen and Lavi are attacked by Count Krory, and Komui, the creator of the virus, must quickly find a vaccine.

Amid the chaos, Allen learns that someone elses memory has been implanted in him?.