Right, well, there?s this manga I read years ago. I?d say, around 2010. It?s about this guy who gets dragged into this prestigious school on top of a mountain or something. He?s not a student of the school. Thing is, the students there have powers or something like that, but he doesn?t. So he uses a card I think?? Can?t remember clearly, but somehow he has powers. Oh, he has a love interest whose dad has something to do with the school.

Pretty certain it's Mx0. Hopefully it is what you're looking for.

Yes, that! Thank you so much!