My Gentle Mr. Devil

A frivolous two-faced demon that attacks x An earnest silly angel who endures it. To fulfill his dream, the angel Nuoqiu takes on the peculiar job of becoming a demon's investigator. The one he's investigating actually claims to have known him for a long time. Angels and demons don't mingle, but the more they get to know each other, the more Nuoqiu is getting the feeling this demon is different. "It's as if... I'm actually starting to like him?"