The Captain and leader of Alpha Team, a fictional elite special forces team of the 707th Special Mission Battalion in South Korea. He followed in the footsteps of his father, a retired Sergeant Major, into the military and graduated from the Korea Military Academy at the top of his class. Si Jin cares little for the politics of war and believes in protecting and defending those who need help, his country and his men's honor, even if it means having to question his superiors' orders. His light-hearted approach to life and witty sense of humor make him popular with his team and subordinates but Mo Yeon quickly realizes that it is his way of deflecting her questions about his job and coping with the pain of losing comrades. At the end of the series, he is promoted to Major. He falls in love with Mo-yeon at first sight but gets rejected by her three times.
