Close sisters who came to their favorite uncle's house in the city from the countryside during summer vacation. Ao, the older sister, is a horny girl with a strong sexual curiosity, and Kina, the younger sister, is innocent, quiet, and clingy. The uncle is bewildered by the lewd questions and flustered by the glimpses of panty shots. Taking advantage of his aunt's absence, they tease and play pranks on the uncle who is manipulating them. Losing themselves in their sweaty, tanned bodies, their rationality collapses…
