Thanks for this - very helpful. I am off to Okinawa in a couple of weeks and want to rent a car when I get there. I would never have thought of asking my CC company what cover they provide - always thought the coverage was on the insurance policy you bought when renting the car.
Has anyone rented a car in Japan using an old UK paper licence? I am concerned even with an international drivers licence they might not accept it as it has no photo.