A young wife who is worried about her figure, thinking that her butt might be sagging recently. On the other hand, her stepson is actually very concerned about such a big-assed stepmother. One day, the stepmother purchases corrective underwear rumored to make her butt beautiful from a mail-order catalog. When she picks up the real thing, there's a hole in the butt part! But she tells herself that it's inevitable because that's the design that makes it effective, and when she actually tries it on, it's quite tight and constricting... Honestly, her pussy is also compressed, and her clitoris is stimulated and it's dangerous... While she was fidgeting, wondering what to do, her stepson sees her! For now, she asks her stepson to help her take it off, but it has the opposite effect, and the stepmother feels more and more good. Even the stepson, who sees the stepmother's erotic ass making her feel so good, gets horny and the atmosphere becomes strange... In the end, the stepmother and stepson end up having sex on impulse. I never thought that the underwear I bought for the purpose of a beautiful butt would promote estrus...