One day, clumsily, Ye-won leaves a message on the school website to reply to Eun-sung's impolite message. She is shocked when someone calls her cell phone and threatens her. Gradually, her best friend, Lee Kyung-won, tells her who Eun-sung is. He sends Ye-won a text message: He will wait for her in front of the main gate. She is so scared that she and Kyung-won decide to jump over the school wall. Unfortunately, the moment Ye-won jumps, Eun-sung is standing exactly at the other side of wall. She falls on him and their lips meet accidentally. Raising his voice, Eun-sung asks her to take responsibility; she is astonished. His friend explains that Eun-sung has never even held hands with a girl. Since she is the first girl who kissed him, as a consequence, she must marry him.