One town's very like another when your head's down over your pieces, brother
-- Murray Head --
The most important thing is your determination to push yourself and to make the most of your opportunity to learn and use Japanese while you are here.
If you have the determination, then even in big cities you can avoid other foreigners and can easily place yourself in situations where you have to use Japanese.
If you don't have the determination and place yourself in a more rural area to counteract that, then you'll just spend your time sitting alone in your room and being miserable.