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Mixed martial arts has been legal in Japan since least the 1980s, Pancrase began to held.
Pride FC for much of early 21 century was the preeminent Mixed martial arts organizations until it was discovered it was being run by the Yazuka.
Video Mixed martial arts in Japan
Domestic organizations
The major MMA organizations in Japan are Rizin Fighting Federation, Pancrase, Shooto and ZST.
Maps Mixed martial arts in Japan
References
Source of the article : Wikipedia