One day, when Shota came home, a girl he didn't know was talking to his mother. The girl was "Sachiko", the daughter of her mother's friend. She has come to Tokyo from the countryside, and although she looks plain at first glance, Shota gets excited when Sachiko's big breasts can be seen through her clothes. And he plotted to set a naughty prank on Sachiko's huge breasts.
