You must have a valid passport and an onward/return ticket for tourist/business "visa free" stays of up to 90 days. Your passports must be valid for the entire time you are staying in Japan. U.S. citizens cannot work on a 90-day "visa free" entry. As a general rule, "visa free" entry status may not be changed to another visa status without departing and then re-entering Japan with the appropriate visa, such as a spouse, work, or study visa.
All foreign nationals entering Japan, with the limited exceptions are required to provide fingerprint scans and to be photographed at the port of entry. This requirement is in addition to any existing visa or passport requirements. Foreign nationals exempt from this requirement include special permanent residents, persons under 16 years of age, holders of diplomatic or official visas, and persons invited by the head of a national administrative organization.
For more information about the Japanese visa waiver program for tourists, Japan's rules on work visas, special visas for taking depositions, and other visa issues, you should consult the Consular Section of the Embassy of Japan at 2520 Massachusetts Avenue NW, Washington, DC 20008, tel. (202) 238-6800, or the nearest Japanese consulate. Please visit the Japanese Embassy’s website for location details. The U.S. Embassy and U.S. consulates in Japan cannot assist in obtaining visas for Japan.