Southern Japan, and Tokyo. The areas I mentioned above, but I have to say in Hiroshima besides their HQ, clubs, gambling dens and businesses, I did not see them at snack bars or Karaoke, which is big over there. Tokyo they are a dime a dozen, and they come in from surrounding areas as they have business there. Osaka you see them a lot. Even when you dont see them, you know they are around. A friend of mine who was a guide to me over there, father was a Yakuza member in Fukuoka which is Yakuza central and I believe him, but I have never been there, so I am just taking his word for it.