>>24539175It's originally from SIR's 2013 new year's comic:
https://sirartwork.tumblr.com/post/71280699540/my-latest-comic-for-fit-panel-by-panel-to
It seems to be based on a later upscaled version (pic is the older cutout from 2015), you can see clearly that Kant is quite ripped following the original model.