Residing in Japan is a vampire clan, which Karin is a part of. However, she stands out due to her condition of overproducing blood. Rather than feeding on her prey, she offers her excess blood to unsuspecting individuals. Despite this, Karin is able to pursue her education alongside her peers. But when transfer student Usui Kenta arrives in her class, Karin's blood production inexplicably skyrockets in response to him. Adding to the dilemma, Kenta accidentally discovers Karin's true identity...