Speeding Fines

[MsJenkins]

We just got back from Japan and had a delightful time. We are wondering what the fines and penalties are for speeding in Japan. We had just arrived in Japan and our hotel driver was driving us into Tokyo from Narita, it was raining, there was an illuminated sign(in red) on the side of the road that said "80", I assume that was the speed limit? Anyway, our driver was doing 110, he was faster than most of the other cars and was rarely passed.

Another day we had a private tour and our driver told us he had on occasion driven 180 km/h on the way to or from Narita when his passengers were late for a flight.

What is the fine for speeding in Japan? Surely doing 180 must be a huge fine. We also thought Japanese drivers followed the rules strictly.