Karin Maaka, a peculiar vampire who defies norms by roaming under the sun and resting at night, conceals her supernatural lineage from her unsuspecting town. When Kenta Usui catches her biting someone on his first day at her school, misunderstandings ensue, prompting Karin to distance herself from him. Determined to mend the situation, Kenta discovers Karin's unique predicament—she involuntarily produces excess blood, risking nosebleeds if not released. As Kenta grapples with this revelation, the challenge arises: can he safeguard Karin's peculiar secret?