Minsu quits the company if he takes it because he is far from home. So, as a special measure, I will stay at my friend's house for a while. Min-soo falls in love with Jae-seok's older sister Yoon-jung at first sight. Meanwhile, Jae-seok decides to start living with her girlfriend Hae-ju at home. Min-soo and Yoon-jung are alone, and love grows...

When I was a high school student, my sister was a sexy friend who kept me from falling asleep with all kinds of delusions every night. Min-soo's thrilling delusion catches fire after she accidentally meets her naked sister at home. After becoming an adult, Minsu and his friend Yong Joon get a job at a sister company. From her sexy friend, Minsu's secret work towards her, who is now reunited as a sexy female warrior, begins...

Min-wook loves his roommate friend Yeongsu's older sister, Sujin. However, Sujin will soon marry a man who meets the condition. I try to hide my heart and wish my sister happiness, When she sees her divorced a few months later, the old feelings come back to life. Soo-jin, who is divorced, will stay in her sister's house for the time being. Min-wook and Su-jin, who have been in one house, are now trying to confirm their love for each other...

Joon-soo learns that his friend Hee-gyu's sister Hee-jin has no where to go after being scammed, so he suggests living with him. The two start living together. They are close like brother and sister but they can never be that. The two start getting funny and Joon-soo can't go to sleep at the thought of Hee-jin sleeping just a wall away from him. Mi-na, Joon-soo's girlfriend notices Joon-soo changing and seduces Joon-soo at his house where Hee-jin is. Is it the girlfriend or the sister?