@Hacete
I mean, teachers don't usually know students' problem
Unless someone reports the incident or they witness it themselves, they won't know
Teacher also can't be generalized
Some teacher won't care, Some care but don't know what to do, Some are afraid if their involvement will make the matter worse, and Some care and try to end the bullying
Actually, the thing I like about this manga is because it brings many different perspectives of how bullying is.
So far, we have been shown the victim's perspective (Tendo),
a bit of the witnesses' perspective (Shinji and this new girl),
teachers' perspective (Shibasaki sensei - teacher who cares, female teacher - teacher who afraid the consequences if she made a move, Aoki - who thinks it's just kids being kids).
oopss. did I write "affair"? xD
But I agree. Even if it's not easy to recognize bullying as an outsider (especially teacher), it's not an excuse. It's difficult, but teacher should be more aware.
Talking about this manga though, teacher responds are still make sense to me