This and post #3456207 are enigmas; while the artists are named, the GilvaSunner youtube videos that the songs are featured in seem to be the only place the art was actually originally posted. Reverse image searches, searching the one findable artist's pixiv, no matter what method I used, I couldn't find any examples of the actual artists posting them.
Edit: I've found the artist's blog, and sourced the images to that instead. Sure enough, though, the images actually were album art.

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