While out promoting Ninja Assassin, director James McTeigue lauded the "incredible discipline" of his movie's star, Ji-Hoon (Rain) Jung. McTeigue said that Rain trained to get into fighting shape "for five or six months."
In a recent interview with Latino Review, Rain corrected McTeigue's statement, saying that his training was even more intense, lasting "eight months, five days a week, eight hours a day."
There is no wire, no camera tricks. I had to make my body fit like Bruce Lee.
Rain said that he does not have formal martial arts training — except for studying tae kwon do when he was 10 — but that he learned "a lot of martial arts" to star in the movie, including "tai chi, ninja techniques, karate ... a lot."
As for learning how to play the role of a ninja, Rain said that inspiration wasn't hard to find.
From when I was young I loved martial arts films so I love ninja, ninja techniques ... you know, in Asia, there's so many ninja films so I saw a lot of ninja films.