One of the pieces of advice I have occasionally seen here and elsewhere that I take the most exception with is to not bother carrying one's passport. I have seen the allegedly "experienced" advice to just leave it in the hotel safe or room safe or elsewhere because one never needs it and it is safer that way.

Folks! In Japan, assuming you are on a tourist visa or waiver, you always need to have your passport with you. If you are concerned about theft, get one of the little "under-clothing" passport carriers. I usually just have it in my shirt pocket or occasionally in a little belt-loop pouch, along with other odds and ends. When out and about, it is always on my person.

It is not like a passport is all that large or heavy as to constitute an unreasonable burden.

I also agree that increased police surveillance is probably related to recent international events and the large conferences going on.