Eun-mi and her husband have been married for 5 years, but they rarley have sex. Eun-mi goes through her SNS one late night and finds a post about 'invitation girls'. After thinking about it for a few days, she signs up for it and gets invited by Hyun-ji and her husband for a new and stimulating experience. Eun-mi shared her experience with her husband and 'swaps' with Hyun-ji and her husband....