Japanese Voltage and Power Cord Settings?

Hi Folks:
I have some audio and video gear that was purchased in the US. I'd like to use it in Japan. Can you advise me on whether there are voltage differences or power cord termination/input differences for Japan vs. the US?

Voltage in Japan is uniformly 100 volts AC with 50hz in Eastern Japan and 60hz in the Western area (Osaka for example). For instance, if you have an amp running at a fixed 120 volts (not universal voltage selectable), best to use a step down transformer.
There are no 3 pin plugs used in Japan -- but two flat pin plugs. You'll find adapters for these in travel stores/websites.
I think Ontjesr means "step up transformer."

Japan is 100 volts and you are requesting a way to use USA (120 Volt) equipment in Japan.

Lots of these on Ebay from $18.00 on up, mostly transformer based.
Outlier, are you moving to Japan? If you use power-conditioning, there are some good Japan-made power conditioners, wave-formers, and such which also act as step-up transformers. Many are made by a company called CSE. They are available used from time to time in high-end shops (the best way to get a comprehensive list of stores in Japan is probably to buy a copy of StereoSound magazine and go through the ads), and also from time to time on Yahoo Auctions (the local version of ebay). Otherwise, if you can get beefy ones on "ebay from $18 and up" which will do what you want, that is a better deal than you will get in Japan. I have heard horror stories of mixing step-up/step-down transformers with power conditioning equipment (have no personal experience doing so and don't know that it is always bad, just know it can be bad in some cases) so I would not recommend bringing US voltage power conditioning equipment to Japan.

Ontjesr's other point about cycles is key. The boundary between "eastern Japan" and "western Japan" for the purpose of mains frequency is the Fuji River in Shizuoka Prefecture and the Itoi River in Niigata Prefecture, and approximately runs along the line you might draw between the two of them. If you will be in Tokyo (or eastern Japan) you might want to check with the manufacturers to see whether your equipment would work with a simple voltage change.
Hi guys:
Thanks so much for the detailed responses. Much appreciated.