BLOOD: THE LAST VAMPIRE

Teropterids are evil beasts which pose as humans and live only to drink human blood. Fortunately for the human world there are groups dedicated to destroying them. A brooding and mysterious girl named Saya is the best teropterid slayer there is, and now, in 1960's Japan, she is sent to a U. S. army base which may be infested... (Source: Anime News Network) — Description from AniList community (anilist.co).