This teacher is an idiot. Either he should have BEEN reported this to the school when he found the hickeys on the girl's neck. The guardian is unfit to care for this child and he should've said something, anything.
She may hate him now for doing so, but it would have been best for her later on.
If he's not going to do the RIGHT thing, then it's best he just stay out of it.
After that long break that the manga took, it came back to just pissing me off.