Something I have always wondered about Japanese wrestling

[Hulk Hogan's Brother]

I have heard that Japanese wrestlers need to be trained in some legit fighting art be it amateur wrestling or martial arts or whatever before they are accepted into a wrestling promotion there. My question is that do the foreign wrestlers who go there, like Rene Dupree and such, have to get trained in some fighting art before they are accepted? Or does this rule not apply to foreigners?

 

[Disturbed]

Jericho went there and I'm pretty sure he wasn't trained in other areas.