Myung-Han is a tall, middle-aged man with gray hair and gray eyes. As the leader of a business empire, he is typically shown wearing formal business attire.
Despite being strict, serious, and uptight, especially with his youngest son Jin-Ho, Myung-Han cares deeply for his family. This is easily seen when he attempted to build a guild not for the sake of money, but for the sake of protecting his family from magical threats. Myung-Han is also wise and unlike some rich people, does not believe that money can buy everything.
At some point in the past, Myung-Han founded Yoojin Construction and built the company from the ground up all by himself, eventually turning it into one of the largest corporations in Korea. He would then marry an unnamed woman and have three children with her over the course of ten years: Jin-Sung, Jin-Hee, and Jin-Ho.
When Jin-Ho revealed to his father that he planned to leave the Yoojin Guild behind and join Jin-Woo's future guild instead as its vice-guild master, Myung-Han was so angered by this revelation that he froze Jin-Ho's accounts and kicked him out of the house. Shortly afterwards, however, Myung-Han discovered that he was mana-intolerant and was beginning to show symptoms of Eternal Slumber due to his exposure to Jin-Ho, prompting his daughter Jin-Hee to return to Korea to take care of him. Despite being told that the disease had no cure, Myung-Han searched tirelessly for a way out of his predicament, eventually discovering that there had only ever been one person who had been successfully cured of Eternal Slumber: Park Kyung-Hye, Jin-Woo's mother.
Despite initially being disappointed by Jinho's decision to work for Jin-Woo, Myung-Han eventually changed his tune and started scrapbooking all of his son's achievements as the Ahjin Guild's vice guild-master. As his symptoms got worse and worse to the point that he'd fall asleep for whole days, Myung-Han contacted Jin-Woo and asked him as to how his mother got cured. Although Jin-Woo was tempted to spill the truth, he ultimately refused to out of fear that Myung-Han was lying to him, leaving a crestfallen Myung-Han with no choice but to accept his fate.
During the Shinjuku Raid, Myung-Han finally succumbed to the effects of Eternal Slumber and fell into a coma, prompting his butler to give Jin-Ho his father's scrapbook and reveal to him that Myung-Han had been proud of his accomplishments, bringing Jin-Ho to tears.
Unknown to anyone, however, Jin-Woo 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 Myung-Han had not been lying to him after all, Jin-Woo then snuck into Myung-Han's hospital room with Stealth and used the Holy Water of Life on him. As expected, it cured Myung-Han of Eternal Slumber and woke him up, shocking both Jin-Hee and his doctors, as none of them had ever expected to see him awake ever again.