Yu-Hon (ユホン Yuhon) was Soo-Won's father and the husband of Lady Yong-Hi, and one of the most powerful and respected generals of Kouka Kingdom before his death. He was the first-born son of Emperor Joo-Nam and as Crown Prince, was original heir to the throne, but he kept his position as head general of the Sky Tribe army when his brother Il inherited the throne instead.
From an early age, Yu-Hon was a courageous, intelligent, and strong warrior who always led Kouka Kingdom's armies to victories in their wars during his father Emperor Joo-Nam's reign. Many people in the country feared and loved him for his battle prowess, especially current Earth Tribe General Lee Geun-Tae, who looked up to Yu-Hon as a mentor, and current Sky Tribe General Han Joo-doh. When it was announced that his younger brother would be king instead of him, many factions in the Sky, Earth, and Water Tribes were very upset about this, considering that Il was weaker, cowardly and wasn't fit to be king since he didn't like violence or war.
However, Yu-Hon himself wasn't angry by this decision, and vowed to protect his brother and their people.
Seventeen years ago before the series began, there was a war between the kingdom of Xing and Kouka over territory. But eventually Xing lost the war and its soldiers and citizens surrendered themselves and were now prisoners of war. During this time Sky general Yu-Hon promised to release them to Xing but instead of them being released alive he decapitated a lot of soldiers and civilians and dumped their severed heads at the gate of the castle. Due to this act of cruelty it caused the citizens of Xing to hate and fear the Kouka Kingdom and see them as devils especially the first and crown princess of Xing Kouren who witnessed this act when she was only a child. Years later after his death this would later cause Kouren when she became of age to rule her kingdom to wage war again on the Kouka kingdom when Soo-Won became king thinking that he would become just like his father.
Also, several years before the series Yu-Hon believed religious priests who could threaten the emperor's power were a nuisance. Therefore, he drove priests (such as Ik-Soo) from the castle. Yu-Hon also deemed the legend of the four dragons as forbidden text, and even attempted to destroy Hiryuu Shrine, possibly due to his firm belief that emperors should have the utmost power.
Yu-Hon is usually a strong and strict person, noted by Yona to be the opposite of Soo-Won. When he was still alive, he encourages Soo-Won, even to the point of telling his son to beat his sickness to death. Due to his strength and intelligence, Soo-Won looked up to him and dreamed that he could fight by his side and die for him someday. However, Soo-Won was blinded to his father's misdeeds, attempting to justify with how his father would handle his enemies and commit the necessary cruelties of war. This was shown when confronted by Yona about the incident that happened with the kingdom of Xing seventeen years ago when his father decapitated a lot of soldiers and civilians who had already surrendered themselves, and dumped their severed heads at the gate of the castle of Xing. This would later cause the first and crown princess of Xing Kouren to hold a deep grudge against his kingdom and go to war with Kouka again after Soo-Won became king.
Yu-Hon was Yong-Hi’s husband. They met after she was attacked by his pet hawk to which he had to rescue her from.