This will sound like a schizo theory but hear me out
>Aidoru is a JP citizen
>flies in clueless western egirls to pimp out and exploit for personal sex and whatever else
>since the girls have no basis for the stay other than "tourism" or "visiting", local authorities likely just wont do much for them
>if they go against him he'll just dump them alone in Japan with no cash and anything else, no chance of going "home" for the egirls besides going to the embassy and saying "my own stupid choices got me here, my Japanese boyfriend dumped me!"
insane I know, but funny to think and realistic enough imo