A war survivor rebuilds his life by fighting everything the world throws at him, literal and otherwise. Ken doesn't learn karate in a dojo, he learns it from bears, bulls, and masters across continents who each teach him something his last opponent didn't. This is a 1973 show that treats martial arts like a genuine odyssey, not a tournament bracket.

After surviving the war as a kamikaze pilot, Ken Asuka drifts into life as a rough hooligan who settles every problem with karate. Reading Eiji Yoshikawa's novels about the legendary swordsman Musashi Miyamoto changes that. Resolving to live the way Musashi did, Ken starts treating karate seriously and sets out to become the strongest martial artist in the world. His journey takes him around the globe, where he faces bears and bulls as well as fighters trained in styles such as Muay Thai and Tai Chi. The story draws on the early years of Masutatsu Oyama, founder of the Kyokushin school of karate, and adapts a manga by Ikki Kajiwara and Jiro Tsunoda into an action, adventure and sports drama.