This is an extreme upscaled of the jpg from the same yande.re post https://yande.re/post/show/418181
The yande.re post has no source: most likely, because the uploader upscaled the image themselves. The jpg being itself most likely also an upscaled image. The image has been most likely detexted to remove the sample watermark from either this https://rokuaka.jp/goods/img/kadokawa2.jpg image or this image https://www.hlj.com/productimages/mdf/mdf20758_2.jpg The reason being that by comparing these images with the one on this post you can see something's off around the places where the watermark should have been: at some place the lines seems less sharp as if it were done by an amateur and the shadows on the skin are weird.

Edit #1: I looked, the other image of this set was never uploaded on yande.re most likely because the other image contained the copyright logo and it probably turned into scribbles during the upscale.