Found in a years old dump from 4chan's /w/ board (as 1426559016029.jpg). I tried finding the original source for this version, but to no avail.

This one should probably be the parent though, since it's both higher resolution and covers a wider view. As far as I can tell, it's not an upscale. The segments on the left and right (cropped out in the sibling post) are also consistent with the style of the rest of the image.

tichusu said:

Found in a years old dump from 4chan's /w/ board (as 1426559016029.jpg). I tried finding the original source for this version, but to no avail.

https://www.pixiv.net/member_illust.php?mode=medium&illust_id=36053611&from_sid=713327940

Thar ya go. That's the artist's pixiv. From about 2013, sound about right?