Via: http://www.tinami.com/view/620175

Via: https://www.pixiv.net/member_illust.php?mode=medium&illust_id=17268781

Based upon information provided by Fiona Jarnefeldt, it is inferred that her father created this Mutant Core as the first generation Armored Core NEXT, showing design similarities to the 002-B and the 03-AALIYAH. It was taken or finished by the Rayleonard Corporation and later by Omer after Rayleonard's fall, and was given to Joshua O'Brien to destroy Anatolia. Despite its monstrous abilities, the 00-Aretha is ultimately destroyed by Anatolia's Mercenary, also killing its pilot Joshua O'Brien. It is later encountered near the Ehrenberg facilities in ACFA, defending them along with Neo Nidus. Weapons Left arm: Large Scale Plasma Cannon (left arm wrist mount) Right arm: Integrated weapon arm (Quintuple Gatling Cannons) Experimental KRB system with impressive range Unlike its smaller predecessors, the ARETHA has only a single set of weapons, but makes up for this lack of modularity by being far more powerful than a normal NEXT's weapons. On the left side, the ARETHA has a large scale plasma cannon with high power, long range, and high velocity for this weapon type. On its right side, the ARETHA equips a quintuple Gatling gun which is capable of shredding AP chewing straight through PA in seconds. In terms of speed, this unit has a unique “Mega” Quickboost that allows the ARETHA to disappear in a blur of red flames, giving the appearance of teleportation; it could also use this in rapid succession, making targeting the ARETHA almost impossible, as well as making any attempt at close combat equal to suicide. Also, the quickboost somehow leaves a missile-misdirecting "flare", although not explicitly referred to as such. As a last resort weapon, the ARETHA also had a prototype Assault Armor, which, while less damaging than its later counterparts, has far greater range. In Armored Core: For Answer it is shown to also have a laser rifle and small Kojima Cannon. However, the capabilities of the LYNX/AI is somewhat poor compared to what it used to be, and the relatively large flat area in which it lands in (after Overboosting into the battlefield), and then fought in makes its once stunning maneuvers quite useless against long range craft (as long as these are able to keep their distance to the ARETHA that is).