Roadtrip to Hanamaki - Some tips about driving on Japanese freeways

Last month I went on a 1,600km road trip from Gifu prefecture where I live, all the way to Iwate prefecture, where the children's author and poet Kenji Miyazawa was born and lived most of his life. It was a long trip and there are many things to talk about, so I'll divide it into a few different posts.
One of the most impressive things about Japan is the number of freeways (toll roads or kosoku-doro) that zigzag all over the country. You can get a tollway credit card (ETC card) and stick it into an ETC reader concealed in the roof of your car or somewhere on your dashboard, which will allow you to pass automatically through any tollgate. It is then tallied up and you pay it off at the end of the month, just like any other credit card. I don't know what the tolls are like in Australia these days, but when I was living in Melbourne you could drive around for the weekend on all the tollways for something like $10. Even at twice the price it would still be a lot cheaper than driving on a tollway in Japan. The total toll charge for me on the way to Iwate was something like 10,000 yen (about US$100) and there were several sections that I chose not to use the toll road. That is a fair chunk out of your travel budget. But tolls are usually half price when you travel on a public holiday, so on the way back it was a bargain at only 5,000 yen.
One of the reasons the roads are so expensive is because Japan is nothing but mountains, which adds a lot to the cost of building them. You'll often find yourself traveling endlessly down a tunnel. The longest tunnel I traveled on was the Mt. Ena tunnel at about 8km. It doesn't sound like much but when you are stuck in a dark dripping tunnel with no emergency stopping lanes it feels like you are in there forever. When you finally get to the end of the tunnel you are on the other side of a big mountain range and sometimes you'll find yourself driving from a cold blue sky into a terrible blizzard, which is quite surreal.
A few pointers about driving in Japan. Cars are expected to make way (if they can) for other  cars entering the freeway, so if your car navigation system warns you that other cars are merging and you see a car coming into your lane, it's best to change lanes if you can or make room for them somehow, because quite often people don't even look.
There are lots of signs that say the speed limit is 80km/h, but that isn't actually for passenger cars, it's for large trucks and other vehicles. For passenger cars the speed limit is 100km/h.
There are a lot of drivers that spend the whole time in the overtaking lane. Some people do that in Australia of course, but nowhere near as much as in Japan, so you just have to get used to it.
There are also a lot of drivers that if they want to overtake you or they are thinking about overtaking you they go right up to your tail and you can see every detail of their face clearly in your rear view mirror. There is nothing you can really do about it, just hope that you don't have to brake in a hurry.
But overall the roads are extremely smooth and far more convenient than ordinary Japanese roads where the speed limit ranges between 50 and 70km/h. Of course if you have time it is much more interesting driving on the ordinary roads, as the toll roads are quite high up and you can't see very much. Not to mention that it is much easier to take in the scenery going 50km/h as opposed to 100 or 110km/h.

An ordinary country road. Sometimes you are better taking the slow road for the beautiful scenery!