In Japan, strange creatures that eat humans are around and they're called "Ghoul". A university student, Kaneki Ken, is riding a normal life and has fallen in love with a girl. But, after their first date it turns out that she's a Ghoul. Being seriously traumatized, he got saved as the Ghoul accidentally died.
What happens when the doctors implant some of her organs to him, in order for him to survive?
[Source: MAL manga synopsis]