Hmm, this does add points to the idea that Haru kind of understand sex stuff, but is oblivious to to the ones happening around her.
Did you skip 40 chapters or something?
Three actually.
There is a possibility that the master was the one who did the cockblocking (and/or did NTR).
Edit: as a side note, that demon girl kinda remind me of modern Amona, wonder if Imp has anything to do with her change in appearance?
I want both the Amona and Imp versions of that story.
The 7 Deadly Sins do better there than the 7 Divine Virtues.
That or some fantasy version of Post-Apocalypse.