The world that obtained technique to life forever because it transplants it to a humanoid with human mind as data established. The human parted from "human being" to "humanoid" having an artificial body. Which of the two existence is correct? The human race has not understood.

Meanwhile, the Chiara princess who is a symbol of "human being" is aimed at. She is a obstructive existence for the humanoid. It puts on the mask called guard, protagonist sent as a spy...

Is she protected, do you betray it?