Jaekyung is the undefeated legend of the Mixed Martial Arts fighting championship. Renowned as a tyrant in the ring and displaying why, Jaekyung is also known as the strongest man in the world. Jaekyung revealed to Dan that he has an unfortunate jinx that causes him to lose in a competition whenever he does not sleep with someone the night before. Calling him repeatedly to have him accept the contract to become on paper his personal therapist, Jaekyung sees Dan as a way to continue winning in the fighting ring. Although savage when fighting, and more than abrupt when speaking, Jaekyung is able to come to recognize what is better for Dan. Over time, Jaekyung enjoys spending time with Dan and becomes more sociable with other members at his gym as well.