The story begins in New York in 1924. Sister Rosette Christopher, a young novice nun from the Magdalan Order, a religious militaristic organization, and her assistant and best friend Chrno, a patient and kind hearted demon, are sent to different missions, consisting mostly in fighting the many different monsters that lurk in the shadows. During one of their missions, they met Azmaria Hendrick, a young girl with supernatural powers that is somehow connected to Joshua Christopher, Rosette’s younger brother who was kidnapped several years ago by Aion, a former comrade of Chrno. Aion is an overly ambitious demon that has big plans for the future of the entire world and will go to any lengths to achieve his great “dream of freedom”. To do this, he needs the help of 7 very special people. What exactly are Aion’s plans, and what does he intend to do with Joshua and Azmaria’s powers?