I was in Roppongi last Friday on my way to Rhythm Rivalry, a very memorable percussion event that was happening at the performance/club space Superdeluxe. (Tokyo events on now)
Passing the Azabu Police Station near Roppongi Hills I noticed a group of photographers - clearly press photographers - waiting in front of it (sitting on left of sidewalk in above photo). The policeman on duty (standing at right with stick) was unfazed by it, and the photographers were in no hurry but looked like they were there for the long haul.
First I thought it may be something to do with the assault on the famous kabuki actor, Ebizo Ichikawa, that had happened about a week before in the same area on November 25; but I saw the same thing this week too: a group of photographers waiting outside Kojimachi Police Station - placing that in some doubt. (More about Kojimachi)
I can only presume that either someone newsworthy was in there and they were waiting for him or her to come out, or that they were hanging around in the hope that that would happen.