I do not know exactly how the uncensored process works in Japan; but from reading the above posts I think I have gathered an okay understanding. It seems to be selling JAV in Japan is only illegal. Why do companies not start a second company ( a shell company) overseas and sell the un-mosaic version through their online store for double the price.
They could region block the site to not work in Japan, like DMM is for us here in the west. And if anyone from Japan wants to buy, all they would have to do it use a VPN or Proxy; that way it is not technically selling in Japan.
selling uncenssored JAV in japan that illegal, selling censsored AV are legal
I've suspected that some uncenssored studios are censsored studio's branch or at least they have connection somehow, because sometimes they shared the same place and same actresses to made some different videos