ノーゲーム・ノーライフ ゼロ.

Six thousand years before Sora and Shiro were even a blink in the history of Disboard, war consumed the land, tearing apart the heavens, destroying stars, and even threatening to wipe out the human race. Amid the chaos and destruction, a young man named Riku leads humanity toward the tomorrow his heart believes in. One day, in the ruins of an Elf city, he meets Schwi, a female exiled "Ex Machina" android who asks him to teach her what it means to have a human heart.