Her stepson is suffering because of her daughter's affair. Rui (Rui Ayukawa) hears this and apologizes, saying it was her poor upbringing that was to blame, then pulls down her stepson's pants. If he's pent up because of her daughter, she'll give him the relief instead. That's the least she can do as a mother. With that in mind, Rui serves him with her mouth. However, her extremely obscene act ends up awakening a forbidden desire in her stepson.