I don't get why he is still insisting to visit that school. I know, that this was his long term goal, but 1st: It is obvious, that this isn't the same school anymore from 5000 Years ago. Too much knowledge has been lost. 2nd: The people in charge of it are dicks! Criminal, blackmailing dicks and a cunt. There is nothing to gain, nothing to prove anymore and the people are troublesome. He should have just lit up that contract of Rina and his own in front of them. (I know. It's a dickish move in itself to not ask her for her opinion on it, but there is no time. You have to show strength right away.) Then he should have teleported over to her, apologized and tell her the story. If she would be mad and wants to stay, I'm sure those bastards would let her.But I can't imagine that. She'll follow him and will return 10 years later to burn that school down.
In the end it's just like many here already said it. His value and that of Rina go through the roof. If they leave, it's the school's bitter loss, not theirs. "Hard" future ahead of Rina or not.
Also, after that blackmailing action of Irene, she's dead to me. I hope he will turn the blackmailing around very hard and will never again share any knowledge with her or at least with a veeeeeery good reason.