One day, Reiko, who lives with her daughter's couple, witnesses her son-in-law, Hikaru, being frustrated and indulging in masturbation. Reiko couldn't take her eyes off that huge thick cock... As soon as she finds out that her daughter is not having sex, she says, "I'll do it instead of my daughter," and she plays with his cock, and she continues to seduce him. Hikaru, who has been accumulating sperm on a daily basis, cannot resist such an invitation from her mother-in-law. Since then, the two have secretly devoured the pleasures of their families, but...