This is the not-so-simple story of a promiscuous professor and her love affairs with five men. Eun-sook has all the male professors wrapped around her finger - but when a popular comic artist Suk-gyu joins the environmental awareness group that she belongs to, he attracts the jealously of Mr. Yoo, a group member who fears that he would steal Eun-sook from him, even though Eun-sook does not return his intense love. What is not known to the rest is that Eun-sook and Suk-gyu attended the same junior high school where they share a secretive tragic history. Back then, Eun-sook was the girlfriend of Suk-gyu's older brother and the three rebellious teenagers indulged in sex promiscuously. Eun-sook worries that her past may be revealed when Mr. Yoo starts snooping around Eun-sook and Suk-gyu's past. Will their secret be kept and will they be together again?