Lee Jonghyun is a handsome, smart student from Hanhwa Highschool of Seoul. He always be number one in both academic and sport. He is very mischievous and love to play a prank to another students. But his life changed when a beautiful transfer student came to his school and shared the same class with him. Gong Seungyeon is a transfer student from Japan. She is really smart and beautiful. She is expert in various martial arts and sports. Her presence become a serious threat to Jonghyun.