This image is all over the Internet, but no one can tell where it came from... until now!
I am pleased to announce that after much research, I have finally found THE SAUCE!
tl;dr - JAV SDMS-526. The screenshot seems to be from 1:08:35, but at a different angle (possibly from a photo taken on-set for publicity purposes)
Full version:
This screenshot is plastered all over the Internet, and many sites put it up as an example of Japanese weirdness - but unfortunately give no clues as to its context or origin.
It is variously titled:
"Ass eating restaurant in Japan"
"Top 30 Weird thing that only exists in japan"
"Susie Sushi"
“Ass social club, am I right?”
"Anus Steak House. Japanese ass-eating restaurant. The only venue on Earth which prides itself for serving sh*t meals."
"Ever Been to a Proctology Convention?"
"Japan really has a knack for understanding what the market wants."
Given how popular it was, and how long it'd been on the Internet with no source provided, I decided to do humanity a favour and try to find out. I had to comb through tons of sites but only one gave me any clues:
ぷるるんお宝画像庫 : AV女優のランク「単体」や「企画」とは何か
On this livedoor page was the cover of a JAV (Japanese Adult Video), from which I got a code:
Unfortunately, this code - SDMT-242 - was not the JAV where the still came from, even if something similar was happening in it. But I found out that it was part of a series called (in English) - "High Class (Secret) Ass Fuck Club" (I can understand some kanji, and it seems a legitimate translation).
There're 5 episodes in the series: SDMS-526, SDMT-242, SDMT-342, SDMS-954 and SDMS-723, and they all have the same theme: men in some underground sex club fucking women immobilised by being stuck in walls.
Unfortunately none of the preview thumbnails or covers seemed to contain this scene, so I had to find the exact production the slow way - by skimming through each episode. Sadly it was in the very last one I saw, but at least I found it in the end!
I do not understand Japanese, but I will observe that this series is very strange. For one it features Baroque (Classical) Music prominently, probably to give it a veneer of class. Then the men keep clapping, even at times like when the women's underwear is cut. Each episode appears to be some sort of contest which one girl "wins" - and gets to be fucked at the end.
Perhaps more pertinently, it is not for everyone as it features varying degrees of non-consent. This is not just the normal JAV no-means-yes moaning - in one (the first?) episode, a group of outsiders of both sexes crash the club and are drugged.
I note that this is not the only example of fucking immobilised women that you can find in JAV - R18.com has some examples in the titles those who bought this production also bought:
SDMS-840 - High Quality (Secret) Big Tit Social Intercourse Club.
SDMS-806 - Creampie OK! Ejaculation Specialist. Cunts in the Walls.
SDMS-838 - VIP SUBSCRIBERS ONLY Ass Toy
RCT-840 - A Brothel With Wall-To-Wall Booty For Ass Lovers
Hope this helps all who have wondered, possibly for years (the JAV came out in 2009 so this still might have been floating around for 11 years), about this mystery!