Out of the three I'd say the true devil would be Tagaki since she is tricking a guy and making fun out of him because it is easy to do so and because she is full of herself.
Nagatoro would actually be the tease seeing as how she only bullies Hachiouji because she noticed that he was a masochist (she doesn't bully other people).
Uzaki would be the annoyance since she is an idiot.
