The expression on Tsume's face looks almost like that of a confused dog, his head tilted to the side as he tries to figure out what is going on. Oh great, he had some sort of a crazy person mistaking him for someone else.

"Are you some kind of nut?" He asks bluntly. At the very least, it's unlikely the teen is being possessed by a demon. The amount of confusion in his voice can't really be faked, and let's face it, that sass is definitely pure teen.