Oboro has a very feminine build with long black hair and black eyes. He wears the female uniform and pretends to be a woman as ordered by [Nishikinomiya|Matsukage] to make his job easier as well as to prevent him from developing any feelings for Anna.
He speaks in a monotone voice. Not much is known about his younger years, but has worked for Mr. Nishkinomya for a long time. As such he has extremely little sense of self, quoting with -
"If Mr. Nishkinomya says that I am a boy, then I am a boy. If he says that I am a girl, then I am a girl. If miss Anna thinks peppers are delicious, then I think they are delicious. If she thinks that pudding is disgusting, then I think they are disgusting. "