Yuki Cross can't remember much other than being attacked by a vampire, when a child. She was saved by Kaname Kuran, also a vampire. The manga begins ten years later, Yuki and Zero Kiryu, the vampire hunter, are the Cross Academy school guardians who protect the "Day Class" (human students) from the "Night Class" (vampire students). Yuki's discovers that her childhood friend, Zero has spent the last four years fighting his transformation into a vampire and he has finally succumbed. She struggles to help Zero fight his bloodlust and to recover her own lost memories, while suspecting that Kaname knows more than he is saying. The love triangle is intense and keeps you guessing. More info at my source.
Karin Maaka and her family of vampires immigrated to Japan two centuries ago. Unlike her family or other vampires, Karin does not feed on blood, she produces it. As a result, she is forced to bite others to expel the extra blood, otherwise she suffers exaggerated nose-bleeds. She also exhibits no normal vampire traits, she can go outside during the day & attends high school. However, the general peacefulness of her life is disrupted with the arrival of a new transfer student, Kenta Usui. Any time she goes near him her blood increases. At first she tries to avoid him but they are in the same class and work in the same restaurant. Kenta begins to think that there is something fishy about Karin and eventually he learns her secret. Her family forces Kenta to watch carefully over Karin, or else. So they inevitably become friends, maybe more? More info at my source.