Infobox Primal Armor
Primal Armor
UniverseAC4 Universe
AppearancesArmored Core 4
Armored Core: For Answer

Primal Armor (PA) is a defensive shield that is created around NEXTs by molding a sustained flow of Kojima Particles around the craft's hull.

The purpose of Primal Armor is to reduce damage taken to the craft's armor. However, absorbing attacks will drain the Primal Armor's effectiveness until it can be recharged. Weapons with high PA Attenuation (PA reduction) and PA Piercing (ability to break through PA) are able to render PA almost useless. Because Kojima Particles are highly pollutive, PA use is strictly banned in developed areas, or areas with civilians. The Kojima Particles used for PA are also used to power Kojima weapons, as well as a highly powerful 360 degree explosion called Assault Armor (AA).


Kojima Particles are released into the atmosphere by NEXT generators are "molded" into a protective sphere by a process known as "Rectification", using an electric charge to maintain its spherical integrity. It is believed that Kojima Particles, when shaped into a sphere of protective energy around an Armored Core, take on a semi-solid state of mass and function very much like a dilatant, except in a "gaseous" form. Primal Armor requires a set minimum amount of KP released in the air before Rectification process can commence. On the other hand, once formed, a Primal Armor can be maintained by simply releasing enough Kojima Particle to counteract whatever decreases PA's integrity. This however, strains the Rectifying process, usually visible as electric arcs along a spherical, invisible surface.

When stable and unused, the armor is invisible and remains in "radiation" form, allowing gases and small objects without significant mass or energy to pass. When any object with kinetic energy impacts the armor, the Kojima Particles automatically shifts into a semi-solid form which is incredibly dense and protects the AC from damage by greatly reducing the kinetic energy of any projectiles passing through that field. In other words, the amount of energy delivered by the projectile is countered by an equal amount of energy exerted by Kojima Particles forming the Armor. This spent energy is then quickly recharged by the generator. This would explain why PA is extremely effective against solid-shell-based weaponry.

Each NEXT frame (Head, Core, Arms, and Legs) are lined with KP Rectifiers, its shape resembling water-cooling coils or slats (although different shapes exist), enabling the process. As each parts vary in shape and functionality, so does its ability to shape and maintain PA, measured by its PA Rectification rating stat. As PA Rectification increases, the more efficient can the part convert KP into PA, hence affecting PA strength.

Overed Boost, also known colloquially as Kojima Boost, uses Kojima Particles already circulated around the NEXT to be used as the booster's "fuel", depleting both energy and Primal Armor at the same time. Another aspect that decreases Primal Armor strength during this process is the gradual depletion of PA due to counteracting aerial friction and other opposing forces. A high KP output as well as high PA Rectification increases the longevity of PA during these maneuvers. Later, as researched by TORUS, PA Rectification rating also affects the performance of Assault Armors.


Although effective against many weapons, there are still ways to break PA; it seems that solid shell weapons that can place an extreme amount of force on a very small point can penetrate Primal Armor, such as Railguns and Sniper Cannons (by virtue of extreme Kinetic Energy) and Physical Parrying Blades (thanks to ultra-dense material composing the spike), negating much of the effect of PA. Also, energy weapons have the ability to almost completely bypass PA, rendering PA useless against them. An example is the HLC02-SIRIUS High-Laser Cannon and Noblesse Oblige's EC-O307AB Tri-Laser Cannon, which for the most part ignore PA and do heavy damage to an AC. Another example are laser blades, which not only bypass Primal Armor, but also takes away huge chunks of it when it connects. Repeatedly beating a PA field will also erode it rather quickly, as this will punch hole after hole in a PA shield, causing progressive damage by hitting PA with one shot before it has time to fully recover from the previous hit. Machine guns and multiple slower weapons firing simultaneously will do this, and will cause the PA to disappear with enough time.

There are other, non-combat related issues regarding Primal Armors. Overed Boost, consuming both energy and Primal Armor, can seriously compromise Primal Armor integrity if overused. High Density Kojima Particles suspended in the air can also interfere with Primal Armor Rectification. The Rectifying process is configured to use lower density Kojima Particles generated from the NEXT, yet the nature of the process itself favors higher density Kojima Particles. In low concentrations of suspended HDKP, when Primal Armor is engaged, the Rectification process uses the particles from the atmosphere to keep itself maintained, yet when decreased, Rectification strain cannot simultaneously maintain the process nor replenish it using lower density KP dispersed by the Generator, and the low concentrations in the atmosphere is not enough to replenish PA strength. As a result, once Rectification can no longer sustain Primal Armor formation, it is "broken" and can no longer be used unless the unit is moved to a clean atmosphere. In high concentrations of suspended HDKP, the Rectification process simply attempts to react with all suspended particles, thereby gradually compromising Primal Armor until it is moved further from the source of High-Density Kojima Particles.

Finally, the necessity of expelling a large quantity of Kojima particles into the atmosphere risks serious environmental contamination, meaning that prolonged combat results in greater release of particles in the environment; alternatively, it also makes fighting in populated areas impossible with PA, leaving a NEXT literally defenseless beyond its own structural strength.

Uses beyond NEXTsEdit

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The Ehrenburg Anti-satellite cannon's high density primal armor. Note its constant "active" state

Primal Armor has also been used on a number of other crafts as well. The giant behemoth in AC4 in the Gear Tunnel had multiple PA rectifiers. Rayleonard's Ehrenburg anti-satellite cannons also had a huge PA field to protect its core energy grid. The cooperatively built Arms Fort Answerer was also noted to have a massive Primal Armor that covered the whole AF, which made long range attacks useless, and was resistant to most NEXT grade weaponry as long as they were fired from outside the PA shield. Also the Answerer appears to have an experimental Assault Armor making this AF hard to take out using melee weapons.


  • The Nine-ball Seraph from Another Century Episode: R seems to have a form of primal armor that can be activated for a limited amount of time.
  • The concept of releasing special particles around a unit for protection is similar to the use of an I-field and GN fields from the Gundam franchise.
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