Monster Hunter 3 Ultimate‘s online play will be region locked.
The announcement came through an interview with Gamereactor and the series producer Ryozo Tsujimoto. Basically you will only be able to play with peers from the same location you’re in. Japanese players will only be able to play with people from Japan. North American players can’t play with Europeans or Japanese players. This is due to the infrastructure of the server, Tsujimoto says.
This restriction is applicable on both Wii U and Nintendo 3DS.