Are you suggesting that porn sex and real sex sound the same in Japan?
I head "porn sex" as "pony sex" for some reason.
Anyway, as a matter of fact,
I am suggesting that they sometimes sound the same in Japan; I have never been there, or had sex with a Japanese girl, but I have read blog posts suggesting that the woman is typically the "receiver" and the man is expected to take care of everything and in some cases doesn't even know what to do with a woman who wants to top. The sounds, such is the claim, result from social expectations.
I swear I have tried to find evidence for my claim for at least 45 minutes. This included watching a 13:58 minutes long documentation on Japanese sex culture by the BBC; unfortunately, that was unhelpful.
My only fruit of my research so far was
this gem from a forum discussion on a similar matter:
The uke (or reciever) is often drawn as shy and somewhat effeminite and frequently bursts into tears during sex.
If he plays a musical instrument during sex, is it a uke-lay-lay?
Can I invoke the pun-jar cross-forums and 6 years in the past? Because I totally want to do that.