The Slum King is the main antagonist of Violence Jack.
After feeling depressed over killing Akira Fudo, Satan created the Slum King to punish himself. The Slum King keeps Ryo Asuka and Miki Makimura, who's arms/legs have been sliced off, as his sex slaves. He is the same height as Jack and has no skin, but instead wears samurai armor. He is the ruler of earthquake-devastated Kanto and has two children, Zubaban and Jannu(who are just as vicious and murderous as their father). He battles against Jack multiple times and finally loses to Jack due to interference from Ryo Asuka and Miki Makimura, which results in a 3 page beheading. He is alive and well after his brutal death in the next chapter and even beheadsZubaban with a one hit kill but was ultimately killed by newly-revived Satan when Satan returns him and Zubaban's head to their true form as Zenon. His face is not revealed until Jack removes his mask in battle.