You can use an International Driving Permit for up to one year, at which point you need to get a Japanese driving license.
No longer true unfortunately. Particularly for US citizens. You can only drive on a foreign license in Japan for as long as you are a foreigner - ie: a tourist. Typically three months, unless you've got a longer visa status.
As soon as your visa status changes to resident, you cannot drive on your foreign license, cannot rent a car, and will be fined accordingly.
The other comment about an International Permit are valid - all that does is provide your local Automobile Association with revenue. They are not needed, anywhere really, as you always have to produce a real license as well...
All the street signs use standard international symbols and I've never been anywhere in Japan where street signs didn't also have English on them (even deep, deep in the countryside.)
I wish! Many places outside major population centers are often only in Japanese. Labels on the Shuto Expressway surface are only in Japanese, as are some signs (try the ARK toward Shibuya for example). It is true though, most places have some
English. Tokyo gets the added benefit of the occasional Chinese & Korean too. Never seen French or German - but who needs that? Ha; tres drole n'ce pas?
since the Japanese sat-nav systems that I have seen only support Japanese language.
Mostly so. Many navi have at least one English option. My Honda speaks to me in English for example, and the Audi/VW/Porsche/Lambo system also takes direct input in English/Romanji and speaks English too. You can also by over the counter new systems in English if needed. Rentals though, different story. See you here one day. Neko.