Midorika and the demonic incantations

She was born to save humankind. A world belonging to humans, was taken away by ruthless homomorphs. These are group of species who were genetically modified by the demons. They took humans as their enemy and tortured them for their amusement. These species also controlled magic belonging to different elements in nature. In this universe, the only one who held magic were the demons themselves. Homomorphs were partially controlled by the demons and hence had magic limited to a certain extent. The demon's sole purpose was to make Earth a living hell for humans. Amongst humans and Homomorphs, their lived an unknown species known as Zoladas. They resided on entirely different planet and no one knows why they existed.
The only ones who can solve such mysteries were Saitekies. They were born when a homomorph marries a human. They had one of the legendary spirits known as the Phoenix spirit. A legendary spirit is acquired when a demon gains complete authority over a person and Saitekies were the only ones who can do that. Hence, they could use magic to an unlimited extent.
No one clearly knows about the origins of Saitekies. Midorika herself was a descendent of the Saiteki dynasty. Every Saiteki serves a purpose when he or she is born but what was Midorika's purpose? Will she survive in the world which hated Saitekies? How will she bring back justice on the face of Earth?