Currency conversions can fluctuate widely; if I could advise you accurately on the future exchange rate, I'd be too rich to be a guidebook writer. Consult a currency-exchange website such as www.xe.com to check up-to-the-minute rates.
Currency -- The currency in Japan is called the yen, symbolized by ¥. Coins come in denominations of ¥1, ¥5, ¥10, ¥50, ¥100, and ¥500. Bills come in denominations of ¥1,000, ¥2,000, ¥5,000, and ¥10,000, though ¥2,000 notes are rarely seen. You'll find that all coins get used (though it's hard to get rid of ¥1 coins). Keep plenty of change handy for riding local transportation such as buses or streetcars. Although change machines are virtually everywhere, even on buses where you can change larger coins and ¥1,000 bills, you'll find it faster to have the exact amount on hand.
Some people like to arrive in a foreign country with that country's currency already on hand, but I do not find it necessary for Japan. Narita, Kansai, and Nagoya international airports all have exchange counters for all incoming international flights that offer better exchange rates than what you'd get abroad, as well as ATMs. I usually change enough money to last several days.
Personal checks are not used in Japan. Most Japanese pay with either credit cards or cash -- and because the country overall has such a low crime rate, you can feel safe walking around with money (though of course you should always exercise caution). The only time you really need to be alert to possible pickpockets in Japan is when you're riding a crowded subway during rush hour or walking in heavily visited areas of Tokyo and other large cities.
In any case, although the bulk of your expenses -- hotels, train tickets, major purchases, meals in tourist-oriented restaurants -- can be paid for with credit cards, you'll want to bring traveler's checks for those times when you might not have easy access to an ATM for cash withdrawals.
ATMs -- The best way to get cash away from home is from an ATM (automated teller machine). Because most bank ATMs in Japan accept only cards issued by Japanese banks, your best bet for obtaining cash is at 7-Eleven convenience stores, which are found throughout Japan, are often open 24 hours, and have ATMs that accept foreign bank cards operating on the Cirrus (www.mastercard.com) and PLUS (www.visa.com) systems, as well as American Express.
Another good bet is at one of 21,000 post offices, which also have ATMs accepting foreign bank cards operating on the Cirrus and PLUS systems. Although major post offices, usually located near main train stations, have long open hours for ATMs (generally 7am-11pm weekdays and 9am-7 or 9pm on weekends), small post offices may have only limited hours for ATMs (depending on the post office, that may be until 6 or 7pm weekdays and until 5pm on weekends).
Other places with ATMs that might accept foreign-issued cards include Citibank and large department stores in major cities. Note that there is no public American Express office in Japan.
Be sure you know your four-digit personal identification number (PIN) and your daily withdrawal limit before leaving home. Also keep in mind that many banks impose a fee every time a card is used at a different bank's ATM, and that fee can be higher for international transactions than for domestic ones. In addition, the bank from which you withdraw cash may charge its own fee. For international withdrawal fees, ask your bank.
Credit Cards -- Credit cards are a safe way to carry money, provide a convenient record of all your expenses, and generally offer relatively good exchange rates. You can withdraw cash advances from your credit cards at banks or ATMs, provided you know your four-digit PIN. Keep in mind that you'll pay interest from the moment of your withdrawal, even if you pay your monthly bills on time. Also, note that many banks assess a 1% to 3% "transaction fee" on all charges you incur abroad (whether you're using the local currency or your native currency).
The most readily accepted cards are MasterCard (also called Eurocard), Visa, and the Japanese credit card JCB (Japan Credit Bank); many tourist-oriented facilities also accept American Express and Diners Club. Shops and restaurants accepting credit and charge cards will usually post which cards they accept at the door or near the cash register. However, some establishments may be reluctant to accept cards for small purchases and inexpensive meals, so inquire beforehand. In addition, note that the vast majority of Japan's smaller and least-expensive businesses, including many restaurants, noodle shops, fast-food joints, ma-and-pa establishments, and the cheapest accommodations, do not accept credit cards.
Traveler's Checks -- While traveler's checks are something of an anachronism now that ATMs have come onto the scene, they're still useful for Japan, where ATMs for foreign-issued cards are limited primarily to 7-Eleven convenience stores and post offices. Traveler's checks fetch a better exchange rate than cash and also offer protection in case of theft (be sure to keep a record of the traveler's checks' serial numbers separate from your checks in the event that they are stolen or lost). Note, however, that in some very remote areas, even banks won't cash them. Before taking off for small towns, therefore, be sure you have enough cash.
Exchanging Money -- All banks in Japan displaying an AUTHORIZED FOREIGN EXCHANGE sign can exchange currency and traveler's checks, with exchange rates usually displayed at the appropriate foreign-exchange counter. Banks are generally open Monday through Friday from 9am to 3pm, though business hours for exchanging foreign currency usually don't begin until 10:30 or 11am (be prepared for a long wait; you'll be asked to sit down as your order is processed). More convenient -- and quicker -- are Travelex (www.travelex.com) foreign-exchange kiosks, with locations in several cities in Japan, including Tokyo, Kyoto, Nagoya, Osaka, and Sapporo.
If you need to exchange money outside banking hours, inquire at your hotel. Likewise, large department stores also offer exchange services and are often open until 7:30 or 8pm. Note, however, that hotels and department stores may charge a handling fee, offer a slightly less favorable exchange rate, and require a passport for all transactions.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.