That faceless expression was really unnerving, considering it entailed an end of life that's coming to grab her by the neck just 5 seconds later.
Should've expected the teacher ngl. But I'm naive so I just chalked it off to another entity. His setup for serial murder really is pretty optimal. He can check his own fate with that mirror, after all, and adjust his status quo whenever necessary.
I still don't know what bumped into Kido. I thought that was a taser, but to think that he got the bruises too...