Good question. I have served in Japan as well. What he needs to obtain is Command Sponsorship.
CNFJ 1300.1R provides amplification upon exactly how this may be done. I recommend reading it in its entirety. You may download and print this instruction at
http://www.psapac.navy.mil/pcs/CNFJ-1300-1R.pdf
That should answer your questions. If you have any further questions, let me know.
Basically, if the prerequisites are not met, and a waiver (exception) is not obtained, you will not be command sponsored, and you will be paying for things out of pocket. Read and follow the aforementioned instruction to the letter and you won't have any issues.