Tokyo: Shiki

"As for the tutoring fee, you can pay me with sex." Kyouhei Saotome, a student, runs into Yuito Jinguuji, a classmate of his—who got into the university he had failed to get into—with the highest score. Born into a strict family where everyone is accomplished, Kyouhei was raised to become a model student, but he finds himself backed into a corner after facing his first setback: namely, failing to get admitted into university. Jinguuji approaches Kyouhei offering to become his private tutor in exchange for sex. Although he dislikes it, Kyouhei gets completely caught up in Jinguuji's sadistic acts as he grows extremely obsessed with Kyouhei... (Source: Taiyo Tosho, translated)