Purpose of Cohabitation: Seung-gu and Yoon-hye enjoy the honeymoon. The photographer, Seung-gu, sells a glance with his senior cousin who is a neighbor cousin on his way to work. Yoon Hye, who has no hesitation in managing her body, goes to the gym for a workout and hears the breakup of Tae Joon, the PT in charge. Tae-jun, who was living in the girlfriend's house, is kicked out with a breakup, and to Tae-jun, where he can't go, Yoon-hye rents out a room for his newlyweds to cover the repair cost of the ride. Offer your own rent. And their purposeful cohabitation begins…