I’ve just seen the other users post about the bicycle note so I figured I’d give another perspective from a driver.
Japanese police are generally much more forgiving if you just cooperate with them and don’t act like an ass!
Case in point, I was driving my girlfriend home and I didn’t stop at a railway crossing like you’re supposed to (it was a small railway crossing at night and I genuinely didn’t see it.) Unluckily for me the police saw and I was promptly pulled over. An officer came out of the car and to my window, explained what had happened and asked for my license. He said I could put my window up since it was cold and went off to, I assume, just do some checks. He came back a few minutes later and asked me if I understood the rule in Japan at railway crossings and I said yes and that it was a stupid mistake by me. He then explained that since it was a first offence, I wouldn’t be given any points or a fine!
Overall, it wasn’t a scary experience whatsoever and I was soon on my way again!
Long story short, just don’t be an ass with them! At the end of the day they’re doing their job and in my case, it was for my own safety!