Google Maps never worked well for me when driving...the voice directions are useless, and I can't be checking it over and over while driving, although it's fine for walking. The GPS is essential, but I wish they would have the Japanese voice slow down when it announces a road/intersection so it's easier to understand and match to a sign.

I usually rent for 1-3 days, so I never took the extra insurance, although I should probably have a look at the liability option give my own liability policy won't cover me in Japan. The damage deductible I can live with for a short trip.

To the OP: where are you planning on renting the car in Japan (and drive it), and have you driven right-sided before?

It's actually fairly easy to pick up. The very first time I rented there, which was the first time I drove right-sided, was in the Mt Fuji lakes region where traffic was fairly easy going, roads were simple and I had the balance of the day to get used to it. Of course later that night after missing the train back, we drove to Tokyo and I had a crash course driving around Tokyo and fumbling for toll coins (make sure you get an ETC card with your car), then driving back to another suburban location to drop the car.

After that interesting experience, I've driven comfortable in Osaka, Nara and Kyoto, and compared to Florida, it's a much more pleasant driving experience all around - but I still wipe my windows when flipping the turn signal, or signal when I need to wipe my windows.