So is either the teacher or the manga is ending "soon". Considering this mangaka really loves to keep the status quo on all of his manga, he only do sudden development near the end.
It is most likely Anthony trying to lure Kate to his side. He is too much of a wild card to be trusted. Worst case scenario, is actually Lewis and we may get the reveal that his soot powers are what allow him to move like a ghost around the house.