In 1999, a teen with a heart of gold begins keeping close tabs on a popular classmate as a favor to her smitten best friend.Bo Ra is 17-year-old high school student. She is good at taekwondo and has a bright and positive personality. She is also a member of the broadcasting club at her school. Woon Ho is a member of the same broadcasting club.Bo Ra is best friends with Yeon Du, who attends the same school. Yeon Du has a crush on Hyun Jin. She asks Bo Ra to find out everything about Hyun Jin and goes to the U.S. to have heart surgery. After that, Bo Ra begins to observe Hyun Jin closely and she falls in love with him.