In the year of 2023, Exorcists and Noah's united in order to the defeat their new enemy, Apocryphos. A creatures that send to kill them and Humans. Allen Walker, is a new girl in Black Order Academy. A place where the candidates of Exorcist, Noah and Finder study to defeat their Enemy. Allen has a secret that no one knows, but what happen if the secret is discover when Apocryphos come and attack the academy?