 Momiji Fujimiya was just an ordinary girl until she learns the hard way about her lineage as the next opponent of supernatural demons who threaten her world when those monsters try to kill her. With the help of a boy called Kusanagi, who cursed to be a superpowerful bodyguard for her, she escapes but not before she is implanted with special crystal called a Blue Seed that allows her to detect the creatures  presence. To protect her and satisfy her demands to help find this menace, she is allowed to join a special government team assembled to fight these monsters. Together, they wage an ongoing war to protect Earth from the supernatural horrors that threaten it.