After some trawling on 4chan it seems like the source is a deleted image on Pixiv, belonging to Oagenosuke (artist #143060). The filename was 58607945_p0.png

SauceNAO seems to be confirming this as well. Relevant tags are shown here too.

However, the brush strokes of this image seem awfully different from the the artist's usual fair.

I'm not sure if this is the rightful artist at all, which may explain the deletion.
However, this image cannot be found anywhere else, so it could also be a case of the artist condemning their work to the void for whatever reason.

Any thoughts?

Edit:

I'll go ahead and update the artist tag. Feel free to reverse this if it turns out this is wrong.