@sun It used to be pretty painless. Just visit the local office of AAA.

Did I tell you that I tried to rent a kei car a couple of times? But every time they forced a substitution to a bigger car with a white plate. They always gave some kind of b.s. excuse, like the assigned car had an accident, and this car is bigger, so it's better, right? I am 100% certain there's a secret policy that denies kei cars to gaijin. Tried both at Toyota rental and Hertz - same result.