Mother Saki moans seductively as she indulges in masturbation. Seeing such an obscene scene by chance, Kazuya was taken aback. Surprise, confusion, excitement. Among the various emotions that welled up, what shook Kazuya's heart the most was Saki's lonely expression. "Mom, you're lonely..." Tonight, Dad is away. Only he can satisfy his mother. Seeing Saki's ecstatic figure, Kazuya decides to cross the forbidden line.