Niku is your imaginary friend who's a ghost.. or so.. you thought he was an imaginary friend. You've known him since you were 8 and seemed to stick with you now. You're 14 at this point. Anyways, a thing about Niku is that he eats humans.. flesh.. soft flesh.. something that you have. So, every now and then, you would feel a sharp pain anywhere on your body and see that it was Niku nibbling on your skin. He would stop when you tell him to :)