Passports
For up-to-date passport requirements for countries around the world, check out the Consular Information Sheets at the U.S. State Department website (start at http://travel.state.gov).
Passport Savvy -- Safeguard your passport in an inconspicuous, inaccessible place, such as a money belt, and keep a photocopy of your passport's information page in your luggage. If you lose your passport, visit your nearest consulate as soon as possible for a replacement. Note: All foreigners must present their passports for photocopying when checking into lodging facilities. In addition, foreigners are required to carry with them at all times either their passports or, for those who have been granted longer stays, their alien registration cards. Police generally do not stop foreigners, but if you're caught without an ID, you'll be taken to local police headquarters. It happened to me once, and believe me, I can think of better ways to spend an hour and a half than explaining in detail who I am, what I am doing in Japan, where I live, and what I plan to do for the rest of my life. I even had to write a statement explaining why I rushed out that day without my passport, apologizing and promising never to do such a thoughtless thing again. The policemen were polite and were simply doing their duty.
Entry Requirements
Americans, Australians, and New Zealanders traveling to Japan as tourists for a stay of 90 days or less need only a valid passport to gain entry into the country. Canadians don't need a visa for stays of up to 3 months, and United Kingdom and Irish citizens can stay up to 6 months without a visa. Note: To prevent terrorism, as of November 2007 all foreigners arriving in Japan are fingerprinted and photographed. Exceptions include children younger than 16, diplomats, and permanent residents of Japan.