I'll be interested to see why this isn't like, a five minute job. Is it a Dangan Ronpa type scenario where the assassins can't allow anyone to know they are the killer? Because otherwise why not just grab Haru, toss her out a window, and job done?Riddle Story of Devil (Akuma no Riddle)
Mr "Dice" Kaiba, her handler, has had her transferred to this Academy's "Black Classroom" so that she can kill the one student there who isn't also an assassin. This dude is a complete dick, played with obvious glee by Tomokazu Sugita. I love the way he chews scenery.