Raiders Vol. 1 (manga)

Irel Clark is a professor’s assistant whose latest find is the “Holy Grail” for member of his profession—literally! But when it turns out that some decidedly unholy individuals are also after the blood of Christ, Irel must drink from the chrism bottle he’s recovered to save his own life.

Immortality leaves something to be desired, though, when undead cannibals walk the earth in constant need of human flesh, and Irel’s newly immortal body is nothing short of an all-you-can-eat buffet!