After the chaos of Armageddon, humanity faces a new threat in the form of vampires. The world is divided between the vampire Methuselah in the New Human Empire and the human Terrans in the Vatican Papal State. Amidst the tension, extremist groups like the Rosenkreuz Order seek to reignite conflict. To combat this, the Vatican deploys the AX unit, led by Cardinal Caterina Sforza. Among the agents is priest Abel Nightroad, a seemingly scatterbrained man who is a skilled vampire hunter. Working alongside him is Sister Esther Blanchett, a courageous nun haunted by her past. Together, they unravel sinister plots and dark forces lurking in the shadows, while navigating their own inner demons.