A world-renowned martial arts fighter, Jaekyung is the reigning light heavyweight champion of MFC's International Mixed Martial Arts Tournament. Very capable at a range of fighting styles, it is why he got the alias "Tyrant". A tyrant in the ring, Jaekyung is also nicknamed "The Emperor" and is considered to be the strongest man in the world.

In training at the gym with his coach, Park Namwook, at some point Jaekyung had burst the punching bag from striking it too hard. 