The Pixiv source was found using SauceNAO, but it's unviewable on Pixiv itself ("creator has limited who can view this content"). Not sure if that means I'm not supposed to upload the pic here.
Also, there's a signature in the corner for a "nightrium", but SauceNAO tied the pic to the artist cino (amairoka). I'm not sure if that's an alias or something.
EDIT: Nightrium is one of his aliases.
EDIT2: Thanks for the Twitter source. SauceNAO can't detect images on Twitter, sadly.
