Choi Bae Dal is a young man with ambition, brawn and a quiet, solitary intellect; the story begins with a short glimpse of how Bae Dal started in his endless search to be great, going from a young street boxer to joining the Japanese Air Force in 1938 during the end of WWII. At the aviation base, he and other Korean men refuse to participate in a kamikaze mission and is therefor discharged and shunned - but not before getting beaten down by proud General Kato Harada, himself a seventh-level Black Belt and indignant to Bae Dal's self-proclaimed Chosun Martial Arts. With the end of the war, he muses on a liberated, yet devastated Korea, comparing it now to his shattered spirit. Staying in Japan, he scrounges a living with his wartime friend Chun Bae, selling a gambling Pachinko Machine.
Japan is now brimming with American soldiers and Yakuza, and Bae Dal and Chun Bae manage to get on the wrong side of a local Yakuza. Despite his best efforts to fight back, Bae Dal is beaten again and humiliated, and it is at this moment he is reuinted with his family's old friend and his own fighter-idol, Beom Su. As a guard for a circus troupe, Beom Su knows the Yakuza all too well, and fights them off, keeping Bae Dal and Chun Bae under his care.
Pleaing for help, Bae Dal begins his karate training once more under the tutledge of Beom Su. He pratices the moves and ideology he learns by seeking to mete out justice to those wrong-doers in the streets. Thus he saves pretty geisha Youko from being raped by Americans, and a romance blossoms. But when his sensei is killed by the Yakuza and Bae Dal takes his revenge upon the criminals, Bae Dal is not only ashamed of his hasty, bloody and vain actions, but tenfold determinded to hone his craft. So he escapes to the solitary mountains for gruesome physical training, in the likeness of legendary swordsman Miyamoto Musashi.
Prefecting his martial arts and his body, Bae Dal then returns to civilization and immediately scours the country looking for a fight, trying to find anyone skilled enough to match him. Soon every dojo and Black Belt is defeated by his powerhouse karate, and even The New York Times is quoted as calling him "The Toughest Man Alive". News of this soon reaches Kato, his old advesary who is now the head of the Martial Arts Union and insulted by his popularity. The Japanese are, of course, unwilling to admit defeat to a Korean, and claim his martial arts is just thug-fighting. Bae Dal must prove to the world that he is the greatest fighter, all the while telling his love Youko that he is always afraid...
