Rika, a beautiful girl raised in Tokyo, had come back to her paternal grandparents' home for a visit. One day, she saw her uncle sleeping on the veranda. His crotch was erect, just a physiological phenomenon. Unaware of sexual knowledge, Rika found it strange and, out of curiosity, touched his crotch, playing a prank by making him ejaculate. Her uncle, who had woken up without her noticing, realized what had happened. Since then, the perception that 'Rika is a naughty girl' spread among the uncles, and Rika became the target of middle-aged men...