Baekhyun was in love with his classroom teacher, Ms. Dareum also known as the popular teacher among of all teachers in Yeonggu High School. But one day, he heard about the news that his classroom teacher was going to move back to U.S.A for continuing the engagement that her parents suggested. How wouldn't he be sad and disappointed? 

Until then, Baekhyun stopped being like the way he was. He changed. A week after Ms. Dareum was gone, the principle told that they were going to have a new teacher on the next day. The principle also told that she was a different person. It makes everyone became so curious about that new teacher, which making Baekhyun more pissed off.