Does anyone know who either of the guest artists are, especially the one who drew the dark skinned girl? They're the same guests from this book: https://e-hentai.org/g/1001316/df96524b66/
With that, I think all but one of Stigaya's books can be found online! At least according to doujinshi.org. Unless it's an already uploaded book with a different cover, there's still this one that eludes me: https://www.doujinshi.org/book/1109656/
If you enjoy works like this, then please buy something from Stigaya! He really deserves it. It saddens me that he doesn't appear to make art anymore.
Also, there's no "moobs" tag, so I used "male: big breasts" instead.