The man was able to twist himself like a pretzel, he was a master of contortion.

or

Pretzels look like a contortion

"Contortion" is a noun. It refers to the act of twisting or bending out of shape or position, typically in a way that is unusual or unnatural.

Yes, there are manga series that involve characters with contortion abilities such as "Kakegurui" and "Kuroko's Basketball." These series may feature contortion as a special skill or ability of certain characters rather than being the central focus of the story.

Demonic origin

Yes