Kyo/Kaoru; Kaoru gets sick of his oppressive parents and takes refuge in Kyo. Well, Kyo's the one who's actually in someone. Nevermind.
Shinya goes to a school where he is usually made fun of and has a mother who abuses him.
Kaoru is kidnapped off the street one day, and finds himself trapped in the seedy underside of a "massage parlor" and unable to escape.