Kuroki is trying too hard, but no one is gonna listed to him, in fact it is clear that they are going to push back harder just to probe him wrong
So he should just retire, he is wasting his time, the junior teachers are hopeless, both of them, hell probably the other teachers are just as bad, and the students are not faring any better, he should cut his loses and go home, there's nothing to do there
Plus it is a small town, the school is probably bound to close off due to a lack of new students, thanks to the aging population and declining birth rate