"I will marry you... Mark my word!" Little Yejin said to her childhood best friend Hyun Bin. While growing up together, her feelings for him started to grow deeper. But the problem is, Hyun Bin didn't feel the same way. She's only his best friend. She didn't know that Hyun Bin is secretly dating her Idol romance writer and her friend of mine, Ha Neul. How long did she wait on him? Will she stop loving him? Or will he see her worth and love her back?