Discovering that my university was located on a hill in a remote suburb outside of town, I found out that the most economical way for me to traverse the 6km from my home to the university was by buying a scooter. Thus started my life as driver in Japan, and thinking back, I have become a pretty good driver by Japanese standards, and probably a lot worse by standards back home. Japanese drivers are very nice and mostly drive safe, and there are not many serious traffic accidents, but boy is their system a lot different from ours.
First of all, I have completely forgot that you are supposed to stop before pedestrian crossings when there are people waiting to cross. This is pretty much never done here, and if you were to stop you could create a dangerous situation in which people are overtaking without seeing the pedestrians.
I also have no idea what the speed limit is on most of the roads that I use, unless I drive in a very rural area. This is because since the Japanese city roads are literally RIDDLED with stop-signs (one every 50 or so meters, no joke), I just go as fast as I can before I have to stop again. Slowing down in densely populated areas is mostly unheard of here. Also, there is no fine for going 10 km/h over the limit, and people will get annoyed if you don't do it.
The traffic rules themselves are also a bit different here, as it is based on the American system and not the European one. For one thing you drive on the wrong side of the road, but that's just something you get used to. The most different thing is that there is no rule where you have to yield for people coming in from the right (or, in this case, the left). Who yields is simply regulated with stop signs and lines on the road, and in the absence of these, the smaller road has to yield. Back home, you would have to yield for people coming out of tiny side roads onto large ones, but that is never done here. Undertaking is also legal here.
Another peculiar thing with driving in Japan is that in stead of giving the "wave" to say thank you in traffic situations, the Japanese honk their horn. In the beginning I was really confused, and often thought people were really mad at me. I still do. I also find it really funny when there are pedestrian crossings on roads that have no sidewalk. There are no rules for wearing clothes when riding a motorbike, and I often see people on 300cc bikes wearing no socks in their pink crocs. If you drive a scooter <50cc, you don't even have to wear a full face helmet. I often see Japanese "gangsters" drive their scooters with a small bicycle-style helmet dangling down their upper backs.
If you are a confident driver, driving around Kyushu Island in a rental is a really enjoyable experience (bring your international drivers license), but keep in mind that their system is a lot different from ours, and try to avoid big cities as much as possible!