Jung Il Woo as Prince Yang Myung - The second Sun, he is the elder half brother of King Hwon. He was always treated unfairly by his father, King Seongjo. Seemingly a carefree man, he had to struggle between his long, unrequited love for Yeon Woo and his brotherhood with Lee Hwon. He was extremely sad and angry when Yeon Woo dies. Eight years later he is entangled in a dynastic fight against Hwon.