Train Violence?

I was so surprised to see this banner add on a trin in Nagoya that I had to take a picture. Unfortunately the hand grips cover up one of the example pictures but the others show fairly nondescript male characters assualting uniformed people, assumably train station staff.

One throws a briefcase at someone's head. Another delivers a headbutt to the back of a woman in a vest. A third is doing after a man with what might be a knife or a shoe. In any case, these are all bodily hard. They're obviously assault. They're obviously illegal. I feel more alien than ever seeing a place where this kind of a sign is necessary but maybe that is the joy of living in a less densely populated area.