Hokuto no Ken Zero: Kenshirou Den
English name: Fist of the North Star: Legend of Kenshiro
Type: Movie, Episodes: 1
Aired: Oct 11, 2008
Studio: TMS Entertainment
Source: Unknown
Rating: R - 17+ (violence & profanity)
Synopsis:
Last of the Shin Kyuuseishu Densetsu pentalogy. A prequel set between Kenshiro's defeat at the hands of Shin and the beginning of the manga. 

(Source: Wikipedia)