It is hinting at that the President is the mastermind behind those girls trying to set katarina up right? Its not that obvious but there's ch 12 where we see that he has a dark side (?) When he said he's not interested in anyone, seems like hes nice to katarina in front of her but schemes things behind her back. Also everyone on the student council was scheduled to be somewhere else at the time ( prbly by him) it does seem fishy. Also it had to be someone is meticulous and smart which is how katarina described him. The only other person it could be is Maria (towards the end of the latest chapter she was acting weird) but it would go against her character profile.
or maybe the president wanted maria and wanted to get rid of katarina so he could get closer to maria but since it didn't work he just kidnapped her ol'e yandere style.
OR he wanted katarina and would have her get kicked out of the academy and then 'save' her and then act like her knight in shining Armour , it would explain why he made the student council not be there and why maria disappeared, maybe because she suspected he was behind it and went to confront him on her own but he like the yandere he might be gut rid of her before she could go back and warn katarina,it would eplain quiet a few things really.
THE PRESIDENT FUCK