Well, this is clearly a sign of the rise of new feudalism and privatization of public space.
Tokyo seems pretty similar to London in this matter; some people with or without cameras have experienced being detained by police for no reasons/charges for a couple of weeks. Protest is another thing that when you have 150 protesters with a permit, you get confronted by twice as many riot police and you get silenced by the end of the day.
There's usually no big media coverage, so the rest of the country will never learn what's actually going on. Now the "enermy is you" slogan is going around everwhere and it's just amazing to see where we've gotten.