[Gwenster]

Just to clarify on what's been said before.
The international ATM's are:

- Post office (have to keep in mind opening/closing hours/know how to spot1)
- Citybank (not alot in Tokyo, look their locations up on their website)
- The 7/11 ATM's

You will find 7/11's *alot* of places.
Google maps also maps out 7/11's by the way.

Do note, that it costs you 200 yen transaction costs at above machines.
Which is at current rate: 2.20 USD.

Japan is a pretty safe country; I carried about 400 USD with me and refilled when needed, wasn't worry about getting robbed, but I was worried about losing my wallet which could happen in the hustle and bustle of things.
I lost my digital camera like that, luckily it was an old Ixus of 100 euro (+i was insured for travel accidents like that) so not my DSLR or wallet, so I was happy about that.

Aside from that. HAVE FUN !