Originally Posted by
bmwe92fan
As someone that has lived in Japan for 15+ years I have never been asked for my passport. But it IS the law in Japan -- and you could be escorted back to your hotel / home to produce your passport -- but it is very unlikely.... But if you are a foreigner that abuses local norms -- I can't speak to that.....
This is like jaywalking in NYC -- technically it's illegal and you can be detained -- but in reality it never happens....
Just as an FYI - I was asked once at the airport post security to produce my passport but that was a joke - I had already left Japan lol...
I've been stopped twice for a passport check (once in Okayama, once in Tokyo), and once for jaywalking

.
At all times I had my passport, and for the Tokyo one, my residency card, too.
However, quick passport checks did the trick (with an admonishment for the jaywalking), and a minute or two later,
fin.
I'm currently living in western Tokyo, enjoying local vegetables and blueberries. Lots of koban (police boxes) seem unoccupied.