It's the omake from ExS-Tia 3 which Ikameshi put on Patreon, hope there's a way to get the whole set of omake comics in digital.
https://www.zff.co/Bhvjd
https://viid.me/9MexS
https://ci-en.dlsite.com/creator/2559/article/364479

*The name of the villain was a reference to "The Blob" said Ikameshi

Finally Ikameshi did something different, I was tired of his combination crotch tattoo+futanari since all the stories were basically the same.

Base +11, Cadavrus +6