Death God Fist (死神拳, Shingami-Ken), also known as the Hero Monster (豪快怪獣, Goukai Kaiju) is the only mysterious person known to be allied on the side of justice. He was created involuntarily by Demon God Fist, awoke the "grip of murder" within him, a dark power which is said to lurk in the hearts of all martial artists. He temporarily lost his sanity to bloodlust, anger and rage, though thanks to the influence of his leader ultima, he was relatively reformed and stabilized, so much so that the hero association now use him as a member of the secret elite squadron. His goal is to seek down and take revenge on demon god fist, his destined rival for stealing his humanity.
Prior to being overcome by the grip of murder, death god fist was the single most talented, famous, and wealthy martial artist in the world, who fought in mixed martial arts tournaments all across the globe, dominating with his superior skills, talent, charisma, and mind games, easily sealing his place as a legend of the modern era and one of the richest entertainers in the world. It wasn't until his fateful meeting with demon god fist, the legendary mysterious being and master of dark martial arts, that he came to knew true power, being beaten down severely, brutally, and onesidedly. The young fighter was cursed during his exchange with demon god fist, who was responsible for awakening the "grip of murder" lurking in his heart, a power which grew and festered to the point of mutating him into the being he is now known as, the infamous death god fist, his destined rival and hated enemy for all eternity.