No Game, No Life Zero

Six thousand years before Sora and Shiro arrive in Disboard, the planet is a battlefield among the sixteen sentient races. Among the casualties of the war between gods is the human species, reduced to a few thousand survivors scraping food out of ruins. Riku leads one of those bands. He stumbles into a discarded Ex Machina android calling herself Schwi — exiled by her own race for asking what a human heart is — and the two of them spend the last season of the old world looking for an answer that will outlive the gods. The film is the founding myth of the world the series opens in.