Hibiki, a nurse, was concerned about her brother-in-law who had become ill. She was Kokoro to see her brother-in-law living a life without energy, and wanted to help him somehow. One day, Hibiki found out that her brother-in-law had been watching adult videos. So, as a sister-in-law and a nurse, Hibiki decided to give him a sex education for his sake, as he still had no idea about the female body...