Ichigo and Kenpachi
School
He had had a nightmare once about Kenpachi turning up at his school with the other shinigami, disguised (badly) as a teacher, because not even in a dream could the captain disguise himself as a fifteen year old student. It had scared him so much that he woke up in a cold sweat. The sight of Kenpachi in a suit, his eye-patch intact and Yachiru on his shoulder in a school-girl skirt, disturbed him greatly.
But when he started to think about it, Kenpachi had taught him some fundamental things that he would never have learnt at any normal school. He had taught him that no matter how much you were broken, you could always get up and get stronger, and that was a lesson he was never to forget. He taught him that no matter how bleak the outcome may appear, anything at all was possible.
He had also taught him that when a blade-wielding manic was bearing down on you, the best thing to do was always to run.
But then, he guessed that was just common sense.