Mikado is the title held by the Imperator of the Novus Orbis Librarium in the anime BlazBlue Alter Memory. This character is originally Saya, the younger sister of Ragna the Bloodedge and Jin Kisaragi. As a child, Saya was born with a frail constitution and was frequently bullied by her brother Jin, while Ragna was more protective and spent considerable time with her. Jin grew jealous of the bond between Ragna and Saya, and after Saya gave him the Nox Nyctores sword Yukianesa, he attempted to kill her. On that same night, Saya was kidnapped by Yuki Terumi and delivered to Relius Clover, who used her body as a vessel for the entity known as Izanami, the goddess of death. Since then, Saya has been possessed by Izanami and rules the world under the name Imperator Librarius, commonly referred to as Mikado.

Under Izanami's possession, Mikado displays a complete absence of emotion and is extremely literal-minded. Her primary motivation is to bring about the death of all life by using the BlazBlue Embryo to convert the world into seithr and create a true BlazBlue. Despite this, traces of the real Saya's attachment to Ragna remain, as noted by Izanami herself. Mikado serves as the central antagonist of the story, orchestrating events through her pawns Hazama and Relius, and later abandoning them when they fail. She also has a longstanding feud with Rachel Alucard. In terms of abilities, Mikado is effectively immortal as the embodiment of death and wields significant authority as the ruler of the Novus Orbis Librarium. She can command the BlazBlue Embryo and manipulate seithr to achieve her destructive goals. Throughout the anime, Mikado remains a static force of nihilistic opposition, with no personal growth or redemption, as her original personality has been entirely suppressed by Izanami.