Hyperdimension Neptunia Re;Birth1 is a video game set in the world of Gamindustri, where four goddesses known as CPUs protect its parallel universes. Unfortunately, during the War of the Guardians between these CPUs for supremacy, monsters began to overrun this world due to Arfoire's influence. During this war, one CPU named Neptune was defeated and fell from the heavens with no memory of who she was. Compa and IF find her and they are soon joined by a mysterious book which contains all knowledge about Gamindustri's history. With help from this sentient book, Neptune, Compa and IF embark on an extraordinary journey across four different nations in order to save their entire world.