Basically I lost this specific image-sequence.
1. Its about I think 10 image give or take
2. Basically an anime gal is laying on her back with her arm and ankle chained to the wall.
3. There is a square paper (makes me think of a seal) on her pussy
4. There is a dildo being inserted in her anus, but basically its like 5 spheres attached together in a dildo and each sphere progressivly gets larger than the previous.
5. The dildo is inserted, then swung up and down then inserted deeper, sideway, then even deeper and goes in a circle motion.
6. finally the dildo is pulled out then reinserted, then they struggle to get it to the 2nd deepest, goes in, then struggle even more to get it all the way in, it snaps all the way in then is turned on.
The dildo end looks like the attached image and its probably approximately that size
Have you tried pixiv?
I have been mainly going through ie the booru boards to try to find it again.
I found this series on 4chan and occasionally tried a reverse image search to find the owner and didn't have any success.