Your Japanese Fiancee needs permission from the US government to allow her to enter the USA. This is called a K1 Fiancee visa.
Fiance visa applications are held only briefly at NVC, just long enough for NVC just long enough for NVC to assign a Tokyo or Naha case number and forward your file via diplomatic pouch to Japan.
Once her petition has arrived in Japan, your fiancee contacts the consulate requesting they schedule her interview.
There are six US consulate service locations in the Japan, but only two consulates, the Consulate in Tokyo or Naha are reponsible for the processing of all Fiance visas. So even if your gal lives across the street from a consulate, she will still have to make the trip to Tokyo or Naha for processing.
Two weeks before her interview date she undergoes a medical exam at one of the five consulate approved Medical clinics distributed around Japan.
Finally she attends the visa interview at the consulate in Tokyo or Naha, to demonstrate she is of good moral character and the engagement is Bona fide.
A week later a courier delivers her visa, and then she can join you in the USA.
I make the process sound simple. But its not. It is easy to make rookie mistakes that can derail the entire process.
By Fred Wahl
Your Personal Immigration Guide