My wife's younger sister, Iori, had a fight with her husband and ran away from home. She's my beloved wife's younger sister, and she's like my younger sister. But there's something strange about Iori. She seems to be jealous of our lovey-dovey couple, and she's suddenly started wearing sexy clothes that emphasize her breasts. And... is she shaking her breasts on purpose? They're really big... At first, I wasn't interested, but she was so obvious, and her breasts were shaking all the time, and I lost my reason...