Happy Sabrina, what makes you tick?

It's the sociologist/psychologist in me popping up again.

I really and truly continue to wonder about these women.

And not just in a skanky "what-do-you-look-like-under-there, and why don't you take your body stocking and your clothes off," gross, anime fetish kind of way, but in a "why-do-they-enjoy-doing-this-for-such-long-stretches-of-time? So Seriously. If anybody knows enough Japanese or has a friend who does. Would somebody please ask these girls for me. I can't read any Japanese so I have no idea how to contact them. I would be very happy to know why they are into doing this? What about it is interesting to them?