Karin Maaka possesses the typical vampire ability to bite necks, but unlike her kin who crave blood, she has an excess of it! Monthly, she must secretly give blood to others, akin to a snake's venomous bite. The presence of her attractive classmate Kenta Usui unnerves her to the point of blushing uncontrollably. To add to the chaos, her latest victim happens to be wealthy and charming, setting off a chain of comedic events at school. Can Karin ever hope for a normal, peaceful life?