Raye is the protagonist of the "Sky Striker" story, directly based on the Yu-Gi-Oh! card "Sky Striker Ace - Raye."
Her background shifts between versions. In the manga, she's humanity's last survivor after a centuries-long war between her homeland Karma and the enemy Spectra Union nearly wiped everyone out. With Spectra drones closing in on Karma's final town, she takes up Sky Striker technology to defend the place and the androids who raised her—the only family she has left. The anime takes a different angle: here she's a naturally gifted fighter with exceptional learning ability and an unusual talent for Sky Striker combat, making her one of the handful of actual humans fighting in a conflict otherwise dominated by drones.
Either way, the story pivots when she meets Roze—another human soldier, fighting on the opposite side.
Content compiled by AnimeList.moe from publicly available sources.
