Seems like there are factions within the shuuki and that not all of them were originally human, gonna be interesting to see the dynamic between these groups. Also its probably too early for the corps to work together with the group of yuuki's sister, though it might be fun if he somehow manages to convince them.
So i guess the "institute" is the one that spread those "peaches" and the anti-demon corps are the one who protecting this "institute" without knowing that this "institute" is the true antagonist.
@theonlykid Yeah, that was my assumption. That or the half-demon girls are a failed experiment that the institute is trying to cover up. Either way, I'm betting it's going to turn out that the institute/government is evil and the anti-demon corps are just being misled, and then there'll be a big fight between the protagonist ladies and the rest of the ADC and so on.