Ai, a mother-in-law, lives with her daughter and son-in-law while her husband is away on a business trip. Although her daily life is peaceful, she masturbates every day to fill the loneliness of her husband's absence. One day, Ai finds out that her daughter's husband, Ichiro, is peeking at her... She is captivated by his huge cock, and before she knows it, she even wants him to use it on her. And when she finds out that he is having no sex with his daughter, she seductively approaches him with her proud K-cup breasts, and continues to seduce him day and night...