Fist of the North Star, Vol. 1 by Buronson

[Viz] In the original classic manga set in a postapocalyptic wasteland ruled by savage gangs, a hero appears to bring justice to the guilty. This warrior named Ken holds the deadly secrets of a mysterious martial art known as Hokuto Shinken—the Divine Fist of the North Star! In a postapocalyptic world, humanity has risen from the ashes of all-out nuclear war to a nightmare of endless suffering. It is a time of chaos. Warlords and gangs of savage marauders rule the broken ruins of civilization, terrorizing and enslaving the survivors. Life has become a brutal struggle for existence and death the only release. One day, a wanderer appears out of the wasteland to bring justice to the guilty and hope to the people—a warrior named Ken, a man who bears seven scars upon his chest and holds the secret of a mysterious martial art known as Hokuto Shinken, the Divine Fist of the North Star!