"Sauce": https://www.pixiv.net/en/users/8662698/artworks/R-18G

Unfortunately, VIOLETSANG's a god damn monster who tends to scatter his works all over Pixiv without giving us any clues.

I KNOW that there ARE full versions of his works; you can find a few of them over here:

https://www.pixiv.net/en/users/38813450

However, most the newer works are still nowhere to be found, and at this point I'm starting to think we need to resort to pestering/bribing this guy to release these works.