The sound of footsteps makes him tense, and while training and paranoia make it easy enough to be on his guard as he slips into a defensive stance, he's clearly unprepared for the appearance that he's greeted by.

Yōkai? Mutant? General freak of nature? He has too little information to really gauge anything at this point. And then the question throws him even further.

"Wha-" Donnie blinks, but he knows he can't have misheard. The added suffix suggests Japanese descent. ...was he in Japan somehow??? But the radio snippets were in English, right? He shakes his head, trying to get himself to focus.

"-how do you know Leo?" he not quite demands.