Classmates

Lee Myung-hoon (played by Choi Seung-hyun)'s father was a southern spy who died unjustly because he was framed. As his children, Li Mingxun and his sister Huiren (played by Kim Yoo Jung) were treated roughly by the authorities. The two people who were suspected of being collaborators were imprisoned and were in a very bad situation. In order to protect his beloved sister, the kind and upright Li Mingxun was forced to take over his father's job and become a ruthless spy. He received cruel and arduous training, and then disguised himself as a high school student and sneaked into South Korea, just to assassinate a technician named Big Dipper. In school, Li Mingxun met a girl named Huiren (played by Han Yeli). What Li Mingxun didn't expect was that the two gradually fell in love. However, Li Mingxun knew that he had a special status and the relationship between the two would not have a good outcome. Not only that, his existence would even cause Huiren's death.