There was a western company, named "Little Mango" that was created for shooting scenes in Japan. They put out like 2 movies I think and perhaps they folded or changed the name.
I also think there was a French guy who appeared in a porn movie with a top Japanese porn star.
I've been to Japan a few times, and yes, it's difficult for outsiders to make a movie. They have no problem bringing Russian and Ukrainian girls to shoot with the men however. I think a clever idea might be to bring some girls from Europe with you who are okay with filming with Japanese guys in exchange for the same company bringing your selection.
Any other way, and the Yakuza might feel disrespected...though they might try to shoot the scene with your girls and then tell you to go home without your scenes produced
