That's probably true, too. The other comment I posted had a link describing a sumo wrestler who was found with cuts and injuries reflecting a serious beating. The cause of death was "heart disease". That may or may not be related to previous cases I've heard of in the sumo world, which seems to have links to organized crime.
With apologies to Terry Pratchett: Japan's philosophy is that if you're going to have crime, at least it should be organized crime.
My fiance did a high-school exchange in Japan and mentioned that people with tattoos weren't welcome at onsen because that usually means Yakuza in Japan, and businesses want to steer clear of all of that. If businesses are making rules like that, it's pretty clearly a non-trivial issue.