I remember reading this manga where there are two guys who can be considered bishonen, they are in an epic duel that takes place every 100 years. I remember there was a flashback to a magical school setting where the two guys were classmates and they had a bunch of classmates. after the flashback, one of the guys meets up with one of their classmates who is an old lady in a forest. whenever I look it up i get Meteor Methuselah but I've read it and Its not it.

Really not sure about this, since I read it so long ago, but Hand x Red?