I...like, Yamori is perceptive enough isn't he? or is it because of how much shit has been happening recently? not sure, but it's been like only a few days from when the vampire almost killed them, Nazuna didn't even want to meet him, and he's now dealing with all this. You can't necesarilly win them all, specially if you're that young.
Like, that lady seems to purposefully try and overload his brain so he'd just give up (and was about to kill him since that failed), but his friend coming in and her baiting both that hard seems to have burnt the braincells he was using to think at that moment. Do wonder how stuff will evolve from here on out.