1. The Japanese unit of currency is the Yen. 1 US Dollar = 90 Yen (as of Feb 10). You can change your money at the airport, at most banks and at post offices. They should have the current rates of exchange clearly on display. You'll need your passport handy when you want to change some money. You can get a cash advance at 12000 ATM machines located at Seven Eleven convenience stores around Japan at any time using your ATM or credit cards.
(You can use Visa, Plus Debit Card, Amex, JCB, Discover & Diners Club. Due to disagreement between MasterCard and Seven Bank, it won't accept any card issued by MasterCard or Cirrus Debit Card.)
Japanese Post Office located all towns in Japan also offer ATM cash withdrawal service for overseas ATM cards. http://www.sevenbank.co.jp/intlcard/index2.html
2. Travelers Checks can be exchanged at most major banks, larger hotels and some duty free shops. You may avoid some commission by using yen-denominated Travelers Checks.
3. The highest denomination note is the 10,000 yen note (Ichiman-en satsu in Japanese). Japan is still a cash based society and relatively safe, thus despite their high value you will see plenty of ichiman-en notes in circulation. The other notes are worth 5,000 yen, 2,000 yen (a newcomer - introduced in the year 2000) and 1000 yen (sen-en satsu). As for coins, there are three silver coins: the 500 yen coin, the 100 yen coin, and the 50 yen coin which has a hole through its center. The 10 yen coin and 5 yen coin (again, with a hole in it) are both bronze. Finally, the one yen coin which is made of aluminum.
4. Credit cards are accepted in most stores and services in Japan, but some cases, such as small hotels, inns, shops, and restaurants accept cash only. And, you may need cash for buses, taxis, trains, and admission to some museums, sights, temples, and shrines.
5. 24hr credit card Emergency Numbers for credit cards:
- American Express: 0120-020-120
- MasterCard: (03) 3256-6271
- Visa: 0120-133-1363
6. Japan has a 5% consumer tax (the price shown on goods is before this tax) and some local taxes for restaurant bills exceeding 5,000 yen and hotel bills exceeding 10,000 yen.