Koji is still passionately in love with his wife Chisato, but recently he has been getting impatient because he has not been able to get an erection properly. Not wanting to be abandoned by Chisato, Koji makes up his mind to turn to aphrodisiacs. However, while Koji is away, Chisato and her son accidentally drink the aphrodisiac. Even though he has not been touched, the depths of his vagina begin to throb and his cock stands tall in the air. Carried away by the sudden heat that runs through their bodies, the two gradually enter into a forbidden relationship.