What street dangers are there?
One example are the notoriously expensive bars in Roppongi, at night there will be touts in the streets trying to convince tourists to join them for a night of drinking. They'll then go to the bar that hired those touts where, after a night of drinking, the tourists will be presented with a bill that's the equivalent of getting robbed.
The line for "acceptable robbery" was "no physical violence" + "someone consensually gives me their money."
Which is still possible (and easily doable if that mark is drunk), but is substantially different from American (and European?) style physical robbery.
Long and short, don't let someone on the street talk you into going into a bar or tea shop or whatever, and especially don't follow them to a second location.