When Hokuto no Ken was picked up to become a weekly series, manga writer Yoshiyuki Okamura (under the pen name of Buronson) was assigned by the editors of Shonen Jump to work with Hara as a scenarionist for the series. Buronson decided to ditch the original premise of the two pilot chapters in favor of the Hokuto no Ken that is known today.

The series told the story of a now grown-up and scarred Kenshiro (who never used his surname and always had his given name spelled in kana) who swears to protect the helpless populace of a post-apocalypse world from the wild gangs of bikers and bandits who prey on them.

After Kenshiro's old friend Shin, the Fist of the South Star, abducts his girlfriend and leaves him for dead, he's left to wander the wasteland where he meets the young, innocent Rin and the not-so-innocent Batt (known as Lynn and Bart in the English-dubbed anime series). Together they meet a wide range of friends and foes (but mostly foes) on their long journey.

Its style of dramatic, shocking, and literally explosive battle sequences caused much heated arguments over its content. Human bodies are chopped, exploded, diced, and smashed in fist-to-fist battles as though they had been struck with highly destructive objects. As Kenshiro blasts his opponents, he makes sounds similar to those of Bruce Lee's animalistic wails.

The story of Fist of the North Star has been told in several different forms.

from Wikipedia