I know I'm combining answers to multiple posts in one post. I realized that after the fact so sorry about that.
I used to be based in Yokosuka, and have friends that used to be and currently are in Okinawa. I lived in Japan for 4 and a half years and my wife is Japanese..... so here's what I know.
On base, there are classes but they are all usually liberal arts type stuff and general ed classes. Very rarely are there any science oriented classes, and if there are, they are all very basic and come without lab portions. Do not expect to get Chem, Micro or A&P unless you can find them online from somewhere like St. Petersburg college.
There are no nursing classes on base, nor will you be able to find an online LPN to RN transition program that will work. There is excelsior, but you would have to travel back to CONUS (continental US as the lingo goes) for your clinicals and practical exams. It would be fiscally impossible unless money is no object since flights are currently running about $1400 round trip for one person.
Off base you will not be able to go to a Japanese nursing school. All forms of professional education are strictly regulated by the Japanese government. You would need to be fluent JLPT level 1 which is a level of native speaking. This level is difficult to attain even after spending 10 years studying the language. More important than that is that you would need to be a natural born Japanese citizen to attend. Also, Japanese nursing schools are typically 4 year programs and most likely your husband is getting 3 year orders. Even if they were to waive all of these requirements, the US SOFA (status of forces agreement) would most likely prohibit you from being a full time student off base as you are in the country strictly as a guest of the United States Government.
As for working at the base hospital as an LPN, you wouldn't be able to do so since the Department of the Navy (not sure about the Air Force hospital in Kadena) only hires civilian RNs with a BSN as the minimal training. You could possibly petition the CO of the hospital to hire you as an RN, but to work as an LPN, you would have to accept a med tech job (which might be available if there are lots of Corpsmen from the hosptial being deployed to Afghanistan) or something clerical.
The only reason I know about the hospital stuff is that I was an ER Corpsman at Yokosuka and plan on going back as a civilian nurse once I finish my BSN (or MSN depending on time) and I've researched the crap out of this.
Good luck with the move and I promise that you'll love Okinawa. Just make sure you don't call the locals Japanese..... they tend to not like it when you do.