The ability to perfectly copy martial arts, Superior Interior Power! Jin cheon rang, who was branded as the “World’s Greatest Killer,” met a miserable death because of this ability. When he woke up, he had possessed the body of his son, Nam Guk cheon, who had committed suicide three days ago. Nam Guk cheon, who had been deeply despised because he was the son of the “World’s Greatest Killer”. “This time, I will become the “First Heavenly Dragon” in my son’s name and take revenge on the world.”