It's 1923 and vampires have existed for quite a while. But now, the number of vampires is increasing and a mysterious, artificial blood source called Ascra has appeared. The Japanese government, in turn, creates “Code Zero,” a unit within the army tasked with taking down the vampiric forces. And there's no better way to track vampires than by using vampires.

https://www.animenewsnetwork.com/enc...e.php?id=23889

Watched the first episode of MARS RED the other day, not sure about it yet. It's based on a play, and it's shows on how it's presented. Will have to see a couple of more episodes to see if it's something I want to invest in.