Myunghan is a middle-aged man with light gray hair and light gray eyes. As a business tycoon, he is usually dressed in formal business attire.
Despite being strict, serious, and uptight, especially with his youngest son Jinho, Myunghan cares deeply for his family. This was easily displayed when he attempted to build a guild not for the sake of money, but for the sake of protecting his family. Myunghan is also wise enough to know that money can't buy everything and that hunters are the most valuable assets in his time.
Shortly after the Red Gate Incident, Jinho visited his father and asked to be chosen over his brother to lead the Yoojin Guild. Although Myunghan easily deduced that his son's stellar raid records were all thanks to Jinwoo, due to having learned beforehand about Jinwoo's involvement in the Red Gate Incident from Go Myung-Hwan, he complied with his son's request and tasked him with recruiting Jinwoo for the Yoojin Guild at all the cost.
At the same time that Jinwoo was announced as Korea's 10th S-Rank, Jinho met up with his father and told him that he planned to leave the Yoojin Guild behind and join Jinwoo's guild instead as its vice-guild master. Unfortunately, Myunghan was so angered by this revelation that he abruptly cut Jinho off from his trust fund and kicked him out of the house.
Shortly afterwards, Myunghan discovered that he was sick with Eternal Slumber due to his exposure to Jinho, prompting his daughter Jinhee to return home to help take care of him. Despite being told by his doctors that the disease had no cure, Myunghan searched tirelessly for a way out of his predicament and eventually discovered that there had only ever been one person in history who had been successfully cured of Eternal Slumber: Park Kyung-Hye, Jinwoo's mother.
When his symptoms started to get worse and worse, Myunghan reached out to Jinwoo and desperately asked him for the truth as to how his mother got cured. Although Jinwoo was tempted to spill the fact that he had the cure, he ultimately refused out of distrust, leaving a crestfallen Myunghan with no choice but to accept his fate. Several days after the Tokyo S-Rank Gate underwent its dungeon break, Myunghan finally succumbed to the effects of Eternal Slumber and fell into a coma, prompting his butler to give Jinho his father's scrapbook and reveal to him that Myunghan had been proud of his accomplishments all along, bringing Jinho to tears.
Unknown to anyone, however, Jinwoo had secretly followed Jinho back to Korea to figure out what was going on. Upon seeing Jinho so distraught over his father's condition and realizing that Myunghan had not been lying to him after all, Jinwoo snuck into Myunghan's hospital room with Stealth and used the Holy Water of Life on him. As expected, it cured Myunghan and woke him up, shocking both Jinhee and his doctors, as no one to their knowledge had ever woken up from Eternal Slumber before.
After Jinwoo obtained the full power of the Shadow Monarch, Myunghan visited him at his family's home and the two of them had a chat. Having already deduced that Jinwoo had cured him, Myunghan sincerely offered his thanks and asked if there was anything he could do to repay him. Although Jinwoo didn't really want anything, he decided to simply ask Myunghan to take care of his mother and sister should he ever die on the battlefield, a request that the latter quickly agreed tio.