Roles. Might be spoilers.

Yes you're seeing right, I have been inspired by our potential Yandere Malleus, so basically Mal is Yan-chan and Yuu is senpai, some students in Yan-sim will be replaced by TW characters, but most of the students will stay. The TW characters will mostly replace male students, since some of the girls have a bigger impact on the canon story (Yan-sim) so they also will in the Au (TW & Yan-sim).

Art and Music does not belong to me!