Kyujyo Kiyo

Kujo Saburou is an "ordinary" high schooler, hyperactive and strangely interested in mysterious (alien) things. He quickly becomes friends with a new transfer student, Shima Ango, who happens to find him in a game of hide-and-seek. But what he doesn't know is Shima's true goal: the extermination of mononoke terrorizing the Tokyo area. Caught in the middle of their fight, Kujo loses his head, unsealing an Oni inside of him…

The background is in the distant future, a post-apocalyptic world after the destruction brought about by Armageddon. The war between humans (Terran) and vampires (Methuselah) continues, as a struggle between two factions: the Vatican and the New Human Empire. Yet, amidst the bloodshed and violence, many desire a peaceful co-existence between the two species. However, standing between them and this goal is the Rosenkreuz Orden, a group of vampire extremists who manipulate the two sides and pit them against each other. To combat them, the Vatican special operations group "AX," led by Cardinal Caterina Sforza, must use everything they have - even a vampire who preys on the blood of other vampires. Adapted from the light novel series of the same name. See AnimeNewsNetwork for the anime.