Isshu region's possible orgin is New York.

[Salnax]

Rainbow Yoshi said:

Salnax said:

Rainbow Yoshi said:

So a small area of Johto is potentially based on Shikoku? Will the rest of Honshu and Shikoku be used or will other International areas be translated into a Pokémon game? 

Shikoku is not really big enough for a whole game, and I'm not sure how they'd tie in another part of Honshu while keeping the game interesting. My guess is that we're going to see some international areas for a while. London is a possibility, but Nintendo and the Pokemon company have a history in the American North-West (Pokémon USA and Nintendo of America are both based in Washington state), so maybe a Seattle-based game is in the future.

Washington is unlikely in my opinion, though some aspects are suitable. British Columbia has a higher chance.

It doesn't have to be just Washington. The entire former Oregon territory would be a good region, with lots of forests, coasts, big cities, huge mountains, a bit of the Great Basin to the South-East, natural parks, etc. I'd imagine it would be pretty similar to Johto and Kanto, just with a different orientation.