From ShoujoMagic:

After failing the entrance exams to her school of choice, Hiyoko Osora gets an acceptance letter from SM Academy. But she didn't even apply or take its exam! When she arrives, there's something amiss--all the students are...monsters!? And the head of the student council says he's her fiancé right before he sprouts giant href='http://www.mangaupdates.com/groups.html?id=3614' onclick="window.open(this.href, '_blank'); return false;">Black Wings! What strange href='http://fate.tainted-reverie.net/' onclick="window.open(this.href, '_blank'); return false;">Fate brought Hiyo to SM Academy, and what supernatural href='http://fate.tainted-reverie.net/' onclick="window.open(this.href, '_blank'); return false;">Fate awaits her after this!?