The world nearly ended after a devastating earthquake. It was dubbed "the earthquake that opened the gates of Hell". Most of the Earth's population was wiped out. Those who survived faced a desolate world. The strong and the rich ruled over the weak. Various warlords ruled over their own domains and the most powerful and ruthless of them all was called the Slum King.

Only one man dares to go against the Slum King - A man who stands over 7 feet, wields a 40 cm long jacknife and possesses monstrous strength. This man is Violence Jack. Their feud starts after Jack kills the patrons of a fine restaurant (thugs of the Slum King) in order to get food to feed some starving children.

Violence Jack can be considered to be a sequel of Devilman. The world was destroyed in the battle between Devilman and Satan. Satan was saddened after having killed Devilman. He decided that the world should not have ended that way and created the world of before the Apocalypse. He then turned himself into the most vile of creatures (a mute and limbless wretch) and created the Slum King to torment him.