This was very strange. I was standing around Shibuya crossing, talking to my friend, and I had my camera around my neck when one of these four girls bent forward and posed for the camera and made a V symbol (standard in Japan when posing for a photo). I made this double-take WTF gestures in mid-conversation and then realized that she wanted her photo taken. When I held up my camera they all posed and I took two shots and they went on their way. This is not the first time this has happened.
...yet when I take photos surreptitiously I get dirty looks. C'est la vie.