Until my husband mentioned that filming people in Japan without their permission is illegal, I had never even considered that the privacy laws here might be different.
I went searching for information on the internet and found an excellent write up by an anthropology professor in Osaka regarding this very issue and providing guidelines based on what legal precedents he has found as well as comments from photographers and photo-journalists working in Japan.
It seems that in Japan you can be sued by a person in one of your photos who has been harmed in some way by the depiction, for example if they were photographed in such a way that it harmed their reputation, and that it is likely the case will be found in favour of the victim and damages can be quite high. Many of the photographers questioned in the article posted their work on English language sites or in foreign newspapers so the chance of damage was greatly lessened.
My overall sense from reading the 7 articles was that this is an ambiguous area, not as safe as America/UK where photographing people in a public sphere is fine; but not exactly illegal, though it could be characterised as damaging in court. Is it better to be safe than sorry, or hope that people viewing themselves in a film or photograph don’t decide they want to sue?