Yes, and the reason is, that they have a very strict social code of conduct, which is why people there take great care of their public (official) persona.

Because of this pressure, people need vents to express what they think about in private and the last thing they want is to connect these to their public persona, which would have much more severe social and business impact than in western countries.

There's also a very prevalent and unfortunate number of perverts as well. It's no wonder women wouldn't want to show their identity. The fact that they have women-only cabins in the public transportation systems is telling enough.

The used schoolgirl panties vending machines probably do not help, either.

http://www.snopes.com/risque/kinky/panties.asp

I have never seen one of these machines and I couldn't tell you where to go to find them. There might be a few fake ones somewhere in Akihabara to appease the Japanophile weirdo crowd and I'm certain Snopes is correct about them being around ~20 years ago, but as near as I can tell these things no longer exist.

I can't comment on the vending machines, but the panties are sold in S&M stores still and it's quite disturbing. (Disclaimer: I noticed them as I was following a friend through den den town.)

Maybe they are more active than us, actually using those online accounts, whereas Facebook for me and my acquaintances is just a way to publish socially-acceptable meaningless crap from time to time, not to mention lots of people I know with Facebook accounts are just lurkers.