Within the world of Gamindustri, there are four continents with a goddesses, or CPU, that rules with it. Planeptune, Lastation, Lowee, and Leanbox. However, during a battle to see on who gets the title of True Goddess, one particular CPU, Purple Heart of Planeptune, gets defeated and gets thrown off of Celestia. Reawakened as her human form Neptune, she soon sets her sights alongside with her new friends Compa and IF, to the find the four Key Fragments in order to free the tome Histoire. All the while Arfoire, the messenger of the being known as Overlord Momus, is wary of her presence and is on the hunt for not just Neptune, but the other goddesses of Gamindustri as well.