A night out should be well planned there when you cannot read or speak the language. It is a regular habit that people, even citizens, have a card for taxi drivers with written instructions where their home/hotel/destination is since street names and house numbers/addresses are a mess. Security is good, also my friends assured me it's quite safe at night in Tokyo and so far I have not found any reason to complain. Also Tokyo gets good security reviews. When you plan to go out at night alone I would confine myself to the local area and explore what's on there. It is a mega city so there are many spots that offer nightlife. If you want to explore the true Nippon in your area I would do walks through the little lanes and housing areas. If you stay close to one of these. It is different when you must drive a distance from your stay to more remote and tiny neighbourhoods.