GAAAAAA! This is a subject close to my ummm, heart, yeah, heart. I strived to meet lesbians or bi-females my entire year in Japan with NO luck. Zero, zilch, nada. Granted I didn't go out enough but...
In my experience (in Japan) it's been that whatever you do in private is fine but in public you need to maintain the most "normal" apperence possible (btw I don't believe in the concept of "normal"). Even though the birth rate is low in Japan you can't deny how important family is to most Asians. So being openly gay is a sign that you aren't going to continue the family, which is the biggest sin.
Generally I think gay men are more visible in most cultures. I wish I knew where all the lesbians are hiding!!! >_< An aside to the whole shonen ai thing--I think that those stories are appealing due to the fact that the guys are pretty (hot) and most of it involves relationships and us girlies love relationships, so double your pleasure, double your fun. That brings me to my complaint about the lack of Yuri!! Where is the hot girl on girl action?
Lately while trying to plan a trip back to Japan I could only get info on ONE lesbian bar in Tokyo. ::weep:: but I WILL go, even if I have to pay a cover and a table charge. If there are any lesbians or bi-females, PLEASE make yourself known.