Haruka, a married woman, became interested in the health method "anal sunbathing" that was talked about on the Internet, and it became her daily routine to spread her anus and enjoy sunbathing in the daytime, when her husband was not looking. One day, she decided to hold a home party to cheer up her subordinate Sanada, who was feeling down after making a series of mistakes at work. The three of them got excited saying that it was a free day, and as they drank more and more, Sanada got drunk and ended up staying over. The next day, Haruka enjoyed anal sunbathing as usual, but Sanada woke up and found her...