Ryuken’s Story: The Judgement Day

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!

(Source: VIZ Media)

A deeper look at the childhood and history of Jagi, one of the four Hokuto brothers, and an important villain in the original Hokuto no Ken manga. 

Includes the one-shot: Hokuto No Ken - Ryuken Gaiden
An alternate version explaining the choosing of Ryuuken's successor and the nuclear apocalypse in the Hokuto No Ken universe.