After the Kanto Hell Earthquake reduces Tokyo to rubble, the giant drifter Jack wanders the wreckage of the Kanto region, clashing again and again with Slum King, the tyrant carving out territory from the ruins. Around them, survivors improvise their own laws in neighborhoods the government has abandoned. Set in the same fractured continuity as Go Nagai's Devilman, this long-running manga plays as an alternate sequel to it, with figures from that story turning up in the wreckage.