Nao, a rural girl, came to Tokyo after graduating from university. Because she had not found a job and did not have a place to live, she stayed with her older sister. However, every night she was bothered by the actions of her older sister and brother-in-law. Being a young girl, she was very curious about it, so when her sister was not home, she put on provocative underwear and went to her brother-in-law who was sitting reading the news on the couch...