Well would you look at that. An adult that came back in time to where he was a child, but who is still not using this as a prétexte to date the other childs it's age.
The other manga i know who did this was Re:Life. I think handling this topic seriously, and not brushing it off as simply "I'm the same age as them now", is very rare and very healthy. Yeah Kanbaru is a full grown adult, she should not be attracted to High school Kids. I'm glad the author gave her a real adult persona, instead of just ignoring it.
It still sucks really bad for the poor kids that have grown attached to her, and those who love her. But she's assuming the fact that she's an adult and that's the right thing to do imo.