Kou Yamori struggles with the intricacies of love like any other typical middle school student. Unable to comprehend societal norms surrounding romance, he decides to stop attending school, viewing conformity as pointless. Unfortunately, his idleness only results in insomnia, pushing him to wander the streets at night. One chance encounter with Nazuna Nanakusa, a unique girl who believes people stay up late due to dissatisfaction with their day's actions, changes everything. Nazuna welcomes Kou to her home, even offering to assist him with his inability to sleep by sharing a futon with him. Despite his reservations, Kou pretends to be asleep, only to be bitten by Nazuna. The bite exposes Nazuna's vampiric nature, leaving Kou initially believing that it will transform him into a vampire. But the process is more complicated than he could have ever imagined. A person must be bitten by someone they genuinely love to undergo the metamorphosis. Kou now has a new objective - to fall in love with Nazuna and become a vampire.