I have respect for many institutions in Japan, but the police are not one of them. They know how to put on a show and harass innocent people, but they would be hopelessly lost and vastly undertrained if they were ever presented with a real challenge.
I was with a Japanese friend in Tokyo (near Takaido) last Sunday when he was stopped about 2 am on suspicion of bike theft for nothing more than a broken headlight. How that could be the basis of anything but a cooked up show of force I still haven't figured out.