In the year 2021, mankind was decimated by the epidemic of Gastrea, a parasitical virus, and is forced to live within Monoliths, which are created from Varanium: a metal that is able to subdue Gastrea. Soon, the "Cursed Children", children born with the Gastrea virus who are able to control it, which gives them superhuman abilities, are discovered. Due to the Gastrea virus' intervention, the Cursed Children could only be female. Civil Securities are formed to specialize fighting against Gastrea, operating with the pair of an Initiator, who are cursed children, and a Promoter, serving to lead the cursed children. Ten years after the epidemic, Rentarō Satomi, a high school student who is also a Promoter in his childhood friend Kisara Tendō's Tendō Civil Security, along with his Initiator Enju Aihara, receives a secret mission to prevent the Tokyo Area's destruction.
