Mars Red takes place in 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," an unit within the army tasked with taking down the vampiric forces. And what better way to track vampires than by using vampires? Created by Lieutenant General Nakajima, this unit has historically been in the business of information war, but has been re-assigned to solve the vampire crisis. (Source: Funimation, edited)

Taichi Keaton is a half-British half-Japanese archeologist and SAS veteran of the Falklands War. He solves mysteries and investigates insurance fraud for Lloyd's around the world. (Source: ANN)

Shio Ogura is a Japanese high school student, who is visiting Taiwan on a school trip when she is suddenly attacked by monsters. Agents known as "E-Gene Holders" from the government agency DOGOO also arrive, who wield weapons infused with the spirits of historical figures. Shio is revealed to also be an E-Gene Holder when the soul of Oda Nobunaga awakens after she tries to rescue a friend. (Source: Wikipedia)

Nana Komatsu is a helpless, naïve 20-year-old who easily falls in love and becomes dependent and clingy to those around her. Even though she nurses ambitious dreams of removing herself from her provincial roots and finding her true calling, she ends up traveling to Tokyo with the humble reason of chasing her current boyfriend Shouji Endo. Nana Osaki, on the other hand, is a proud, enigmatic punk rock vocalist from a similarly rural background, who nurtures the desire to become a professional singer. Putting her career with a fairly popular band (and her passionate romance with one of its former members) firmly behind her, she boards the same train to Tokyo as Nana Komatsu. Through a fateful encounter in their journey toward the metropolis, the young women with the same given name are brought together, sparking a chain of events which eventually result in them sharing an apartment. As their friendship deepens, the two attempt to support each other through thick and thin, their deeply intertwined lives filled with romance, music, challenges, and heartbreaks that will ultimately test their seemingly unbreakable bond. [Written by MAL Rewrite]