[godwine]

Actually, so far I had no problems finding ATM that will accept my bank card, outside/inside tokyo. Almost all postal outlet will have a machine that accept standard ATM cards.

You can find postal outlet by looking for this symbol "〒", or in Kanji: 郵便局, pronounced yuubinkyoku. If you really need to ask for direction (in which case, the person probably will reply in Japanese anyways or will just point), just simply "Sumimasen, yuubinkyoku wa doko desu ka?" - Excuse me where is the postal office?

Good luck