This movie is based on the true life story of Choi Yeong-eui (who later changed his name to Masutatsu Oyama), the founder of Kyokushin Karate. Choi was born in South Korea in 1923, immigrated to Japan in 1938, and founded the Kyokushin Karate organization in 1953. Currently, Kyokushin Karate is practiced by more than 12 million practitioners in over 120 countries around the world.
The end of the film refers to the kumite, a series of 2 minute matches. Oyama completed the 100 man kumite 3 times in 3 days as a demonstration.
The story of Oyama inspired the look of Ryu in the Street Fighter videogame series.
Bae Dal shaves his eyebrows because it would cause him great shame if seen by others, thus forcing him to remain isolated to train.
The title refers to Bae Dal's dream of being a kamikaze pilot, which is translated as "divine wind."