I think Ada should try to befriend Kaye. at least she already kind enough to help her at class. whether that will change the original plot story and will prevent her from going back to real world, at least by doing that, Kaye won't kill her, whether she will become demon lord or not. I mean, at least Ada can prevent her death at the Kaye's hands right? that's one thing is sure for now, and she definitely can afford it. especially they have become a desk friend.