Karin Maaka

The protagonist of the show. Karin is a "blood-producing" vampire (増血鬼, zōketsuki — literally "haematopoietic demon"); rather than needing to acquire blood from humans, her body produces too much blood instead (polycythemia). To make matters worse, her blood levels increase dramatically whenever she senses unhappiness in those around her, or if she gets embarrassed about something. This results in frequent nosebleeds, followed by anemic symptoms such as light-headedness, which causes frequent visits to the school nurses office so she can rest. She does not suck blood from her "victims"; rather, she injects her surplus into them instead. This has the effect of making her victims very lively and positive.