My original tumblr post was here. This image was researched by Bacchus at ErosBlog as part of the “Δ commission.” The research was originally published at Hedonix as “Δ 046 – Project 513 Going Badly.” Here is what Bacchus found.
Visible in this image are the words “Project 513” and the url “huntang.artstation.com”. That URL leads to the web page for the artist Angelina Stroganova from Moscow, Russia. This image is visible there along with a grayscale version of the same art. This artist also has a presence on Deviant Art where the same artwork appears.
Although there are several references to Project 513 in connection with other artworks on this artist’s pages, I was unable to find any information in English on the significance of the Project 513 name or what it represents.