Seo-yeon is being tutored by Woo-hyeon who is younger than her. She grew interested in her tutor, Woo-hyun, the first time she met him, and he is also fond of Seo-yeon. Seo-yeon succeeded in seducing Woo-hyeon with the help of her friend Min-joo. Even if Min-joo is aware of what Seo-yeon feels, she approaches Woo-hyeon. Seo-yeon gets mad at her best friend when she met Woo-hyeon. Min-joo, aware of the fact that it's her faultis also angered by Seo-yeon's appearance and tells her to meet Jeong-soo, her friend. Seo-yeon is also angry and tells Min-joo that she have to meet Jeong-soo as well. A bittersweet story about a man who is a very close friend is just about to start.