OMG BEST ANIME EVER. LIKE HANDS DOWN BEST ONE.
Let me sum it up without revealing anything. Yuki is a girl who was taken in by the headmaster of cross academy. She has no memories of her real family at all. After Kaname- the dorm president of the night class- saves her from a vampire trying to kill her. But he is also a vampire and it is very clear from even the first episode they both really care for each other. It is now years later and they both still go to Yuki's adoptive dads school. Which there is a night and day class. Day class for humans, night one for vampires. And the humans have no idea that they are vampires, so the headmaster made something called a Disciplinary Comity. Which only consists of his daughter Yuki and son Zero. Which he took both of them in. Will Yuki fall for the vampire who saved her life, the guy who is her "brother", or will she fall under the pressure.