Originally Posted by LapLap

I'll testify to that. I went out alone on my first visit to Japan (before I met my husband) and felt very safe.

I'll mention that on my first night in Tokyo I arrived at the club I was heading for in Azabu Juban too early and wound up walking up to Roppongi (because I didn't know any better ) and then down again, and whilst in Roppongi some weird Japanese guy did follow me for a little while. But he was easy enough to shake off, and I never felt particularly threatened (just a little creeped out).

Never had any other problems as a lone female.

If you're at all concerned, I'd say avoid Roppongi (it has a greater sleaze factor than almost any other part of the city). Take the usual care, don't drink too much and keep your wits about you, but I'd say Tokyo has to be one of the safest cities to go out in at night. Especially if you get back on the last train. (Whatever you do, don't try and get a taxi for any destination more than a 3 or 4 stops away on the subway. Not if you want to stay on budget. And don't ever assume the taxi driver knows where he's going, or that he'll give you the right change back.)