Fifth Jerusalem is the current capital planet of the Galaxy Federation, and seat of the central legislative judicial, and administrative agencies. The headquarters of the S.O.C.E. is also located here. As the name suggests, it is the fifth capital of the Galaxy Federation after Lost Jerusalem. Fifth Jerusalem also encompasses a large administrative space-station in orbit tethered to the planet by a large-scall space elevator. The station serves as a spaceport and as an administration center.

While briefly glimpsed in Episodes I & II, Fifth Jerusalem is the stage for a good portion of the story at the start of Episode III. Shion Uzuki is invited to Fifth Jerusalem by newly-promoted KOS-MOS Project Chief Engineer Allen Ridgeley to witness KOS-MOS appear in a combat demonstration against the Federation's new secret weapon, Ω Res Novae.

Later in the game, Abel's Ark reappears, and the planets of the Galaxy Federation start disappearing one by one. In a communication between the group on the Durandal and Helmer on Miltia, it's mentioned that contact with Fifth Jerusalem was lost, strongly suggesting that the planet is already gone.