Neptune, the goddess-like ruler of the nation of Planeptune, and her sister Nepgear are warned of an approaching "CPU Shift Period" in which the people of the world of Gamindustri may abandon their divine rulers for newcomers. Before they can prepare, a mysterious old game console transports the two sisters into the ruined, monster-infested Zero Dimension. There they meet Uzume, a fellow amnesiac ruler, and team up to reclaim the devastated land, only to uncover a far larger scheme threatening both their world and Zero Dimension alike.