Tokyo Ghoul Season 1

Ken Kaneki is a bookworm college student who meets a girl names Rize at a cafe he frequents. They're the same age and have the same interests, so they quickly become close. Little does Kaneki know that Rize is a ghoul - a kind of monster that lives by hunting and devouring human flesh. When part of her special organ - "the red child" - is transplanted into Kaneki, he becomes a ghoul himself, trapped in a warped world where humans are not the top of the food chain.