As expressed in the tags, this a doujinshi cover and here's a tweet by the artist with a little information about the comic- and the link in which you can order this R-18 work.

Gotaru said:

As expressed in the tags, this a doujinshi cover and here's a tweet by the artist with a little information about the comic- and the link in which you can order this R-18 work.

And here's the Pixiv link with more info.