Kojou Akatsuki is secretly the Fourth Primogenitor, the most powerful vampire alive, hiding in plain sight on the artificial island of Itogami. Attack Mage Yukina Himeragi is sent to monitor him, and to eliminate him if he becomes a threat, but his powers only awaken under specific, often embarrassing conditions that keep giving her trouble. This manga adapts part of the original light novel, following Kojou and Yukina's uneasy partnership as more of the island's supernatural residents take notice of him.