I dunno...the prequel to Mebius:loop was in a Sanae/Reimu/Aya rape compilation, where Yukari had Aya gang-banged for peeping on Reimu. Could this be between the two? Then why is she still getting molested, without Yukari around? Then again, she also promises to service the guys who helped her get revenge in Mebius:loop, so this might be that...but she promised that in a pretty mind breaky way, so why does she look so upset in this? Did she change her mind? Is it all just a dream, as implied by the ending? If so, how much of this series is just dreams? Is Yukari sending the nightmares or something?
Ugh. I'm thinking about this shit to much. I'd commission this book and find out if I didn't hate mind break so much.