Think of Japan in the same terms as the USA:
We have "states" (50 of them). Japan has "prefectures" (47 of them).
We have "cities". So does Japan. However, a "city" in Japan has to have a certain minimum population. US cities don't generally have any population minimum requirements.
If a Japanese "population center" doesn't have enough people to qualify as a "city", it's considered a "town" or "village".
We have "counties". Japan has "guns" (pronounced "goons"). A gun may contain several cities.
JARL has quite a few awards. WAJA is for working all 47 prefectures; very similar to WAS.
I'm working (on again, off again) on the JCC (Japan Century Cities) and JCG (Japan Century Guns) awards. Currently I'm at 523 cities and 319 guns.
You can get current city/gun lists from the JARL website, if you're interested.