[sarasi]

I agree with the above, if you were looking for one of the least safe areas in Tokyo, Shin-Okubo would probably be it as it is on the fringes of the red-light district and has a kind of transient population.

That said, it is still safer than most big cities, so provided you don't regularly walk home alone at 3am it should be fine. Takadanobaba and Otsuka are safer than Okubo, but you always have to be a bit careful when walking around late at night in big cities, Tokyo is no exception.