>>132321
It's probably a lot rarer, but it likely happens anyway from time to time, just like graffiti on trains in Japan.
Part of that would likely have to do with the way trains are worked. Most trains carry a guard or conductor which means someone in the rear cab of the train watching so riding on the back is largely out of the question. Even for wanman setups, most trains in Japan have large windows between the cabs and passenger areas so someone inside could see unless it was at night on an empty train.
Riding on the top is a possibility but Japan's loading gauge means potentially quite low wire height in some places. That and unless you were out in the countryside, you'd get caught.
I'm sure more than a handful of people want to surf the Shinkansen like that Wolverine movie but low wire height does present a serious danger (as we've seen with someone who went bzzzt on top of a Shinkansen a few months ago). Though there are anchor points and antennas, but they're in places where you'd probably be seen by the conductor in the rear cab anyway.
Someone also went bzzzt while climbing on top of a train under the influence of alcohol. Because they were American, they were made out to be some sort of hero by their own as usual.
I think the fines would just be a small part of things. Railways are mostly private which means they can and will sue you for every yen you have, especially if you being caught causes delays. Then they can hand you over to the cops for some likely jail time.
As I recall, there was a sign I saw on the fence of the Shinkansen tracks (really, compared to how conventional railways are fenced off with almost nothing, Shinkansen trains are a bloody fortress in most places) in the countryside. Shinkansen has its own regulations and so is even fenced off when running alongside regular trains. The sign mentioned something along the lines of fines up to the equivalent of millions of $ and a decent amount of jail time.
[1chan]