Saya is the former Imperator of the Novus Orbis Librarium, and the younger sister of Jin Kisaragi and Ragna the Bloodedge. She is currently being used as a vessel for the Goddess of Death, Izanami who is the True Main Antagonist of the Series.

Under the possession of Izanami, it is clear that Saya has become devoid of all emotion and extremely literal-minded. She is obsessed with making the world die and will stop at nothing to accomplish her goal. Cutscenes shown in Ragna's story show that Saya was very dependent on her brother when she was little, and was a normal and confident young girl. Even as she is being possessed by Izanami, the Goddess remarks that she can 'feel' the strong attachment that the real Saya has towards Ragna.Izanami is devoid of all emotion and extremely literal-minded. She is obsessed with making the world die and will stop at nothing to accomplish her goal.