Thanks for sharing the link!
If you go outside of large cities, where public transportation is generally excellent, you might find a car useful.
Every time we go visit our in-laws, we go somewhere by car - mountains, historic sights, etc. Most of the time it was my father-in-law who drove but the last time i got my international driving license translated (right, there is no Japanese translation by default) I drove his car a little bit. I was never stopped by the police, so I am not sure if translation of the driving license is the only thing you need to do. That is why this post made me think that I need to study the subject a little deeper when I go to Japan next time. And of course renting a car is interesting, I remember my father-in-law was genuinely worried about his car when he saw me drive :)