Ken Asuka, a former kamikaze pilot, turns to a life of violence, resolving issues with karate after being inspired by Musashi Miyamoto's philosophical approach to life as depicted in Eiji Yoshikawa's novels. This shift in perspective prompts him to dedicate himself to karate, mirroring the legendary swordsman's discipline. The manga upon which the series is based was created by Ikki Kajiwara and Jiro Tsunoda, drawing from the real-life experiences of Kyokushin Karate founder Yasunobu Oyama.