In the future, great war wipes out all of civilization on earth, fire burns every thing to the ground, nothing left, just ash and charcoal. Humanity is gone, got replaced by robot, machine, and ai.

Robot take human place, build the civilization from ash, but like human, they fight each other, creating war, wipe all of enemy. Until two faction remain, Spectra Union and Kama.

Time by time, Kama teritory is shrinking because endless attack from Spectra Union. To avoid from destruction, Kama start with Sky Striker Ace Project, creating and training human to protect this land. After several failure, Raye comes as a hope.

In the end, Spectra Union is fall and war is end, so because nothing to do now, she decides to walk around the world to see human legacy with Roza. After several years, she feels if she can safe humanity if she can prevent the war, so she back to Kama to build time machine.

After 7 years, time machine is invented, with Roze she back to past, but they're too far, 15 years early from the war. Because that, she hide her identity, waiting for the time.

Sky Striker Ace Raye, from Sky striker archtype, Yu-Gi-Oh! TCG/OCG. Oh, come on, she's not minor in this scenario, how a kid can have licence to use gun and explotion? or even be mecha and aeroplane pilot?