Nazuna Nanakusa (七草 ナズナ)

Nanakusa Nazuna is a vampire who entered a deal with Kou Yamori in order to drink his blood. She is quite short is stature, standing just a head or so higher than a middle school boy. Nazuna is a very laid-back individual. She's not overly friendly but she has a very relaxed presence in most situations and is willing to talk to just about anyone and prefers keeping on good terms with everyone, including people that would normally consider themselves her enemy because of her vampirism.

(Source: Yofukashi no Uta Wiki)