Sayuki, a filthy tutor, is asked to help her co-worker's son with his studies. When she finds a porn magazine in the student's room, she starts masturbating in front of him, displaying her lewdness. She then licks his erect cock and forces him to perform cunnilingus on her. She then invites him into the bath, saying that her pussy is all wet, and while stroking his cock, she promises him a reward of sex, saying that if he gets 100 points on the test, she'll let him put his cock in.