Sora and Shiro, brother and sister, are brilliant (but unemployed) gamers whose fame has spawned urban legends all over the Internet. One day, they are summoned by a boy named "God" to an alternate world. There, God has prohibited war and declared this to be a world where "everything is decided by games," even national borders. Humanity has been driven back into one remaining city by the other races. Will Sora and Shiro, the good-for-nothing brother and sister, become the "Saviors of Humanity" in this alternate world?