How would a woman have sexual intercourse in the Heian times? With the ridiculous amount of clothes they wore and the ridiculous amount of hair they had, I imagine it was fairly difficult to do many everyday things, sex not included. Obviously this might ruin some possibilities. How far would they get undressed? Shikibu Murasaki was curiously silent on the subject. (On that note, would the courtesans of the later Edo period have removed the white make-up and elaborate coiffures? In shunga they’re still aloft, but I’m not sure if I trust that. It seems unlikely)
Well, they didn’t wear a bazillion layers all year - I believe for certain parts of summer one could see the nipples? Silk gauze that stood out from the body for coolness? I think I got that from the Liza Dalby kimono book, which I haven’t read for some time and I believe is currently borrowed, so I’d appreciate corroboration that that was indeed in the Heian period.
And as for your elaborate waxed Edo hair, well, you slept in it on one of those ghastly pillows, right? Maybe that’s why they’re so often pictured having sex sitting up. Can’t imagine what your crazy hairdo would look like when smushed on one side. (Well, yeah, I can. 
)
I think the question applies equally to other societies that wore lots of odd clothing: Europe in the 18th century, etc.
Also, not all societies necessarily have sex totally naked. Keep in mind it’s possible just to rip off the ol’ undies and go for it. I don’t see why the Heian layers would prevent this type of thing, since everything but the undies (if they were even wearing them) is open at the bottom.
Not that I’m saying that was the case.
I haven’t seen Liza Dalby’s kimono book, but I’ve read her novel The Tale of Murasaki (eleventh century… approximately Heian, right?) and nipples visible through gauze are mentioned, yes.
Well, one of the bottom Heian layers is very long red pants. That could prove to be a problem - you’d have to get them off somehow, they’re not open like Victorian drawers or anything.
I think you’re just supposed to write a poem about it.
Even if you could get them off, I doubt you couldn’t get more adventerous than the missonary position. That’s no fun 
?
man sitting [like in a chair but on a low bench or zabuton or futon] woman sitting in his lap impaled facing him, facing away from him.
Woman kneeling doggie style, man from behind.
man lying facing up, woman impaled facing his head, impaled facing towards his feet.
woman lying on her back on a low table, woman lying on her stomach on a low table either way man up on knees penetrating.
Woman standing facing wall and braced, woman leaning against wall facing man, wrapping a leg around his waist.
woman sitting up in something waist height to the man like a fence railing or cabinet.
sheesh, go read Joy of Sex…If she is not wearing undies, she can get laid any way you can while naked.
Actually, they never had sex. Which is why there are no members of the Japanese Heian Court alive today.
First, women of high standing were almost never alone. Even when they were at an assignation they would probably have a trusted maid or two with them who would help them rearrange their clothing afterward. The robes that were worn even during the heights of impracticality in the Heian period were typically many layers of relatively light fabric, like unlined silk or cotton. Like all robes, they were simply wrapped around the body and belted, leaving relatively free access to anything underneath. Finding the “underneath” would probably be your biggest trick. There’s no way anyone would get completely undressed to screw, not unless they really wanted to get caught in the act. A lady needed a few servants and more than an hour (or several) to get properly dressed.
I asked a couple of the history teachers (I work at a high school in Japan) and they said that often people would only wear a cotton robe first layer as “underwear” unless they were traveling. When traveling, both men and women would often wear hakama, which were not terribly different from martial arts hakama worn in aikido and kendo today. Silk or cotton pantaloons were sometimes worn under the robes, depending on the time you’re considering (the Heian period was 300 years long; things change quite a bit over that long a time), but even those would not be a big problem. If you didn’t want to deal with them, you could just leave them off when getting dressed. You would have to plan everything in detail or you’d virtually guarantee your place in court gossip. It’s not like you could spontaneously throw your lover down on the tatami whenever you felt like it when you live in such a small fish bowl as the Japanese court.
There are practical limits to how restrictive clothing can become, no matter how stupid the fashions are. People do have to excrete on a regular basis after all. I’d say that 19th century Western hoop skirts were a bigger pain to deal with than Heian court garb. Women sometimes wore three or four layers of petticoats and a kind of pants underneath those monstrosities.