Model Number: OZ-13MS2
Code name: Epyon II
Unit Type: Transformable mobile suit
Manufacturer: Prototype Mobile Suits, Inc
Operator: Mars Defense Corps
First deployment: Mid AC 216
Pilots: Milliardo Peacecraft, Sidra Peacecraft
Accomodation: Pilot only, in standard cockpit in torso
Height: 16.3 meters
Weight: 7.5 tons
Armor: Gundanium alloy
Powerplant: Ultracompact fusion reactor, power output unknown
Equipment and design features: Head mounted sensors, range unknown
Fixed armaments: 2 x vulcan gun, fire linked, mounted in head
Optional fixed armaments: 1 x shield, mounted on left arm, mounts 1 x heat rod
Optional hand armaments: 2 x beam sword, directly connected to generator, stored in charge racks on waist armor, hand carried in use; 1 x megacannon, hand carried in use

In preparation of the expected conflict with Venus, Mars governor Milliardo Peacecraft, with funding from the Winner Corporation, secretly designed and built several new Gundams to meet the threat. Prototype Mobile Suits, Inc, already well regarded by the governor for their refit of his Tallgeese mobile suit, was again hired to design and help build these new Gundams, one of which was a throwback to the Eve Wars, the Epyon II.

Unlike its predecesor, the second incarnation of the Epyon boasts a more rounded armament, with the addition of ranged weapons such as standard head vulcans and a megacannon. While these round out its armament, the suit is geared toward melee combat, including the same powerful large beam sword and heat rod weapons of the original, as well as the ability to transform into an agile flight mode. While it lacks the brainbending ZERO system, it can still keep up with enemy units due to increased thruster output and the use of cutting edge internal hardware.

After the Tallgeese was stolen by his daughter Sidra, Milliardo would take the PMS-MDC-01SS Gundam Star-Streak into battle until the completion of the Epyon II. When Sidra and the Tallgeese returned to Mars after the Une Conflict, the Epyon II would become Sidra's unit until later in the war.