Vampire Dormitory

Mito, who has no family to rely on, lives on the streets, disguised as a boy. Ruka, a vampire, saves her from a perilous situation and makes her an offer: become his subservient thrall from which he can feed whenever he wants, and she can live with him—in the boys’ dorm. Because her very existence depends on her secret not being found out, every day is a new danger. <em class=de-emphasized>(from manga)</em>

Synopsis from Anime News Network