The story centers on Luna Ishikawa, a second-year high school transfer student who is popular because of her cool and mysterious aura and her commanding presence. Luna excels in her studies and in sports, but as a vampire, she is actually bad at sucking blood. Tatsuta Ōtori, Luna's classmate who tends to blend into the scenery at their high school, discovers her secret. As a result, he becomes her "Mama" so she can practice blood sucking.