I passed on my second practical test. They like to nitpick at the practical test. I think I failed the first time because I didn't pull all the way over to the side of the road before making a turn. They explained this to me, so I passed the next time. I was lucky in that I knew how to speak Japanese. There were other foreigners who didn't speak Japanese, and they took numerous attempts to pass. This was in Yamaguchi prefecture more than 20 years ago.
The written test was quite simple. For the practical test, at the time, you had to request an automatic transmission car for the test if you didn't know how to drive a manual transmission. The test was conducted on a closed course.
Some state drivers' licenses can be converted and others can't. I can't remember how to predict which is which any more.
But yeah, owning a car in Japan is very expensive.