Tokyo Ghoul

Tokyo Ghoul is set in an alternate reality where ghouls, individuals who can only survive by eating human flesh, live among the normal humans in secret, hiding their true nature to evade pursuit from the authorities.

Ken Kaneki, a normal college student who, after being taken to a hospital, discovers that he underwent a surgery that transformed him into a half-ghoul after being attacked by his date, Rize Kamishiro who reveals herself to be a ghoul. This was accomplished by transferring Rize's organs into his body, and now, like normal ghouls, he must consume human flesh to survive. Struggling with his new life as a half-ghoul, he must now adapt into the ghoul society, as well as keeping his identity hidden from his human companions. Read more on Wikipedia.