The year is 2045, humanity is plagued by an enemy thought only to exist in old text and folk tales. Demons pierce the fabric of reality itself to invade earth and consume everything and everyone they can get their hands on. But somehow the demons brought magic with them to our world in the form of a video game like system. Now the defenders of humanity, commonly known as just 'defenders' use this magic system to stand as humanity's shield against the dark tide from beyond our world.

Lucy always admired the defenders, and hated demons, like everyone else alive today. She never though she would have magic access and be able to stand as a defender of humanity. But when a supposedly normal day goes awry and Lucy gets attacked by a demon, that's exactly what she gets. It's just that it comes with a few complications, like being turned into some new form of demon. Now Lucy has to learn how to use her new powers and assume the role that is expected of her. All this while trying to live a somewhat normal life, and trying to hide the fact she is a demon now.