maybe it's me looking into it too much, but maybe the "important thing" is actually the inevitable baby these guys are gonna make when they finally get it on. because the school principal & witch were saying they will finally get a heir or something right when talking? also, the rituals and tests, witch is trying to get them to fulfill the conditions before they conceive a heir for the school board granny for the "200-year arrangement" that is about to come true - they talked about it when they went over to that weirdo house of orders. also the info about priest believing in bloodlines when hinako researched it at the library.. taking away the important thing could mean two things here, maybe the witch actually just wants the babby and is baiting them into failing the deal or maybe the babby doesnt survive if they fail and "taking it away" symbolizes baby dead (if they fail to be patient). btw aliens are real