@Metazoxan still, there should be a reason for the hero to not be acting against the monsters, right? After all, who knows if monsters are the lesser of two evils, what with how much of an asshole the god in sora no otoshimono ended up being, and how mindless angels are shown to be here (at least in following orders).
I mean, no matter how much of an asshole the hero was, he could've just dealt with monster-san if he wanted to, yet he decided to fight the angels that were going to irrupt into monster-san's house.
...Probably because of something like Popa's mother being killed by angels for some kind of heretic act, or just because when angels could've saved her they just didn't, but still.