In the anime series Gundam Seed Destiny, ZAFT creates a new series of advanced mobile suits to succeed their previous generation of Gundams, which were all lost in the previous war. Since the Treaty of Junius bans the military use of the Neutron Jammer Canceller, these new Gundams use conventional battery power instead. However, technological improvements over the last two years mean that battery efficiency is improved, and Phase Shift armor is less power intensive than it had once been. To further improve endurance, ZAFT also introduces the new Deuterion Beam Energy Transfer System, which allows a properly equipped battleship to remotely recharge a mobile suit's battery.

One of these new suits is the ZGMF-X31S Abyss Gundam, a transformable unit specializing in underwater combat. In mobile suit mode, the Abyss Gundam is armed with a beam lance, a chest-mounted beam cannon, several CIWS guns, and a pair of shoulder-mounted shields which each contain 3 smaller beam cannons and 2 shell-firing cannons. In addition, the Abyss Gundam could transform into a streamlined mobile armor mode for underwater combat. In this mode, it was armed with a pair of powerful railguns and four high-speed torpedo launchers.

The Abyss Gundam is initially test piloted at Armory One by Marle Stroud. However, before ZAFT can bring it into active service, Auel Neider of the Earth Alliance's 81st Independent Mobile Battalion steals the mobile suit and escapes with it to the battleship Girty Lue. The Abyss Gundam is later transferred to Earth and operates from the carrier John Paul Jones.

Specifications

ZGMF-X31S Abyss Gundam

Manufacturer: Zodiac Alliance of Freedom Treaty
User: Zodiac Alliance of Freedom Treaty, Earth Alliance
Unit type: prototype transformable amphibious mobile suit
Head height: 17.84 m
Weight: Max gross 92.39 t
Special equipment: Phase Shift armor, Deuterion Beam Energy Transfer System
Powerplant: Ultracompact energy battery
Armament: MMI-GAU1717 12.5mm multi-barrel CIWS x2, MMI-GAU25A 20mm multi-barrel CIWS x2, MGX-2235 "Callidus" multi-phase beam cannon x1, MMI-TT101 Mk9 high-speed guided torpedo launcher x4, M68 dual cannon x2, MA-X223E triple beam cannon x2, MMI-M15E "Xiphias Kai" railgun x2, MX-RQB516 beam lance x1
Pilot: Marle Stroud, Auel Neider