Do you need an International Driving Permit for Japan?

Japan recognizes International Driving Permits issued under the 1949 Geneva Convention only. Permits issued under the 1968 Vienna Convention are not valid in Japan even when the issuing country is a party to the 1949 Convention as well.

For US license holders this is straightforward: the United States is a 1949 Geneva Convention country, and AAA and AATA are the only two organizations authorized by the State Department to issue IDPs. A permit from either is the correct type.

Your IDP is valid for one year from its date of issue, and you may drive on it for up to one year from the date you enter Japan - whichever expires first.

Beware of online sellers offering "international driver's licenses". Those documents are not recognized in Japan and are not issued under any convention.

An International Driving Permit is a translation of your licence into a standard multilingual booklet, issued under the 1949 and 1968 road traffic conventions. It is not a licence, and it is never valid on its own: you carry it with your own licence, and police expect to see both.

It is issued against the vehicle classes already on your home licence, and it never adds one. If your licence does not cover motorcycles, an IDP does not let you ride a scooter in Japan; if it does not cover a heavier vehicle, the permit will not cover a camper or a minibus either. The permit restates what you already hold, in a form the local authorities can read.