Living in a place other than Tokyo... but in Japan

I might move to a place other than Tokyo. I don't know yet though. If so, it would be the first time I've lived in anywhere but Tokyo.
One start-up business is being launching in Okinawa. If I join it, I will move to and stay in Okinawa for about a year. It's like an extended business trip.

The new business sounds very fun and I'm interested in it, so it would be great to join in it. But I have a mixed feeling about it.

Tempting things are;
Above all, building something from scratch in business is in my line, and I like to do that very much.
Secondly, some staffs will go to Okinawa from Tokyo for this project, so of course, the company prepared for dwellings for them and the rent is free. It's a monthly apartment and very small room (TOO small!), but at least I don't need to pay the rent fee and utilities payments for a year.
Thirdly, I've wanted to visit Okinawa... but on sightseeing trip though.

Concerns are;
I LOVE my hometown Tokyo. I've always thought I never want to live anywhere but Tokyo. I've thought when I leave from Tokyo, it is when I live in a foreign country.
Fortunately, the office and the living place are in central Okinawa city. I was born and grew up in Tokyo and I also live in central Tokyo now. I feel it impossible for me to live in the country side.
One more concern is I will be apart from the English-speaking environment. The project will provide its service just for Japanese people and all staffs are Japanese. Analyzing my motivation for learning English so far, it wasn't that I wanted to do that, but I had to do it. It seems to become harder to keep my motivation.

Anyway, it will be clear whether I join in the project or not by this weekend. If it's decided to join, I will have to move early in the new year, and I will get busy.