Plot:- After her parents died in a house fire when she was a young child, teenage orphan Mito Yamamoto spent the majority of her early years living with various relatives who treated her like nothing more than a burden. Years later, one of her relatives kicked her out and left her to fend for herself. Now that she is homeless, she begins sleeping in secret at the ramen restaurant where she works as a waitress until her supervisor fires her for it. In an effort to hide herself and avoid drawing unwelcome attention from curious onlookers, she then begins dressed like a boy.
While looking for work, she unexpectedly finds herself at La Fraise, a well-liked cafe with attractive servers. There, she breaks a vase and slashes her finger, which starts to bleed. Ruka Saotome, one of the servers, brings her to the back room so she can get medical attention for her wound.
Unaware that she is a woman, he licks the blood from her cut until the taste repulses him, forcing her to flee. Later that evening, Mito, feeling alone and hopeless, considers jumping off a bridge to end her life. But, as she starts to have second thoughts, she slips and falls, and is saved by Ruka, who turns out to be a vampire who bites her neck while draining her blood.
Subsequently, he remarks that the taste of men's blood is disgusting and that the blood of an unloved person is much bitter—this explains Mito's earlier cut—and he suggests that Mito take on the role of his thrall. Even though Mito is a girl, she moves in with Ruka at the Hijirigaoka Boys' Academy hostel, where she keeps hiding her true identity by pretending to be a student. She then starts working at the cafe with Ruka and a few other people.