I was hoping we'd get an explanation about where the line is drawn for what the school can provide. It seemed WAY too easy for demons to just keep gaining ranks through something like the battler party. Considering that most teachers, that we know the rank of, are rank 7, it would be weird for them to be able to promote students to the same rank or higher, there had to eventually be a funnel point where the requirements are just too high for it to be that easy. Mephisto's statement to Iruma makes me wonder further about his affiliations. On the one hand, it seems feasible that he is working with Baal, on the other hand, it could also be possible that he has his own reasons to believe that Iruma has the potential to be the king (though I imagine he'll say something like "just kidding" or hand wave it as something connected to the thing Iruma is doing at the beginning of the chapter, but I imagine he'll prove to be more serious than he lets on.) Despite all the mystique around Mephisto, I'm not yet ready to believe he's another antagonist, he might be "working" with Baal, but, if so, I'm thinking it'll be similar to Hawks's situation in My Hero 🤔