Kenshiro is the main protagonist of the Hokuto no Ken series. He is the 64th successor to the Hokuto Shinken killing art. They call him "one of the greatest" in Hokuto Shinken history.
Kenshiro is characterized as the youngest of four adopted sons trained by the previous Hokuto Shinken successor, Ryuken. His origin is revealed during the latter half of the Fist of the North Star manga, in which he was sent to Japan, along with his future nemesis Raoh and Raoh's brother Toki, to escape from their homeland, the war-torn Land of Asura. A different origin is depicted in the first chapter of Fist of the Blue Sky: a newly-born child is brought to Ryuken's dojo in Japan, who names the infant after his older brother (Kenshiro Kasumi, the protagonist of Blue Sky), due to the Big Dipper-shaped birthmark on his head, although later chapters of the manga makes references to Kenshiro's escape from Asura with Raoh and Toki.
Kenshiro is trained in the art of Hokuto Shinken along with Raoh, Toki and a fourth student named Jagi, and is eventually named successor by Ryuken. After surviving the nuclear war, he tries to live in peace with his fiancee Yuria, until Jagi instigates Shin, a jealous rival from the Nanto Seiken school, to challenge, then defeat Kenshiro. Shin then engraves the iconic seven scars on Kenshiro's chest and leaves him for dead. Prior to this event he was more forgiving of his enemies, as shown in a flashback of Jagi's failed assassination attempt against him, in which Kenshiro chooses to spare Jagi's life after defeating him rather than end it. When Kenshiro later fights his old rivals in the present, particularly Shin, Jagi, and Raoh, they all remark on Kenshiro's acquired mercilessness.
The initial story arc centers around Kenshiro's quest to reclaim Yuria from Shin. In the very first chapter, he meets a pair of orphans who follows him in his journey: Bat, a thief; and Lin, a young girl rescued by Ken. Throughout the course of the series, Kenshiro protects the weak and innocent from the numerous gangs roaming the post-apocalyptic wasteland, eventually gaining his reputation as the "Savior of the Century's End". Kenshiro's skills improve through his encounters with members of the Nanto Roku Seiken and his Hokuto Brothers. At the end of the first part, he eventually confronts and defeats his eldest brother Raoh and is reunited with Yuria, and lives with her until she eventually dies from a terminal illness.
The later half of the manga (and the corresponding Hokuto no Ken 2 anime adaptation) sees Kenshiro joining forces with the now grown Bat and Lin, who have formed the Hokuto Army to fight off the now-corrupt Gento Kōken warriors. The story eventually takes Ken to the Land of Asura, where he learns of his Hokuto Sōke heritage and fights against the Warlords who controls the Land of Asura: his estranged blood brother Hyoh; and Kaioh, Raoh's other blood brother. The final story arcs of the manga (which were not adapted for the TV series) sees Kenshiro taking Raoh's orphaned son, Ryu, under his wing, before continuing on his own.
Although still emotionally repressed and stoic like most male heroes in 1980's media, Kenshiro is notable in anime culture for being a sensitive and kind-hearted man who broke the then-ironclad "men don't cry" cultural expectation. He is famous for openly shedding tears, if not outright weeping for the suffering of innocents and the deaths of his few noble enemies. This trait is downplayed in the 1980's anime adaptations, but comes back into the franchise in the adaptations of the 1990's and onwards.