• Mental Models
  • SD Version of the Mental Models
Mental Models are anthropomorphic representations of the "Fleet of Fog" vessels' cores' consciousness. The primary purpose of Mental Models is allowing the vessels' cores to feel past and future and understand the concepts on which tactics are based. Aside from that, Mental Models also grant the "Fleet of Fog" vessels the extra ways of communication and better ways of infiltrating human settlements for reconnaissance or sabotage.

A brief historyEdit

Among the many mysteries surrounding the "Fleet of Fog", Mental Models are actually the one that is the easiest to have answers to. In the original designs - so to say - all "Fleet of Fog" vessels with sufficient computational power of their Union cores were to have Mental Models. However, the "Fleet of Fog" vessels were activated incompletely and did not possess Mental Models during the Great Battle in 2039.

Following that battle, the supreme flagship of the "Fleet of Fog", Yamato, disappeared for a long period of time, reappearing only around 2053-2054. And when she reappeared, she had her Mental Model. From that point onwards, first battleships, capital ships and battlecruisers and then heavy cruisers and big submarines started gaining Mental Models. Even though many vessels of the "Fleet of Fog" may have their Mental Models, some may actually chose not to use one or (like it is the case with U-2501) be forced not to use one for different reasons.

  • In the Yamato's flashback it can be seen that her sister Musashi was among the first "Fleet of Fog" vessels to gain a Mental Model. In the same flashback, the formation of what is believed to I-401's Mental Model is also shown. This corresponds well with Takao's comment that I-401 is one of the oldest Mental Models in existence.

In the most recent times, more and more Mental Models come in close contact with humans. And, among other things, this led to the occurrences of events that would never happen should the Mental Models not exist. Before the Mental Models were introduced, it was unthinkable for the "Fleet of Fog" vessels to run away or have their own opinions on their tasks, which may or may not be the same with the opinion of the higher-ranked commanding flagship; in other words, going rogue was also unthinkable when the Mental Models were unknown to the "Fleet of Fog" vessels. Finally, the emotional simulations ran by the Mental Models create the possibility of the Mental Model developing certain feelings towards other Mental Models or even humans: battleship Hyuuga, heavy cruiser Takao, battlecruiser Repulse all have developed a crush on someone.

Reasons for existenceEdit

According to the supreme flagship of the "Fleet of Fog", Yamato, the Mental Models are an artificial restriction placed upon the vessels' cores in order to give them the feel of past and future and to stimulate the self cultivation. After all, the "Fleet of Fog" won the Great Battle because of the overwhelming technological advantage. Even then, the humans still managed to capture at least one "Fleet of Fog" vessel during that battle. If the both sides of that conflict had same-level technologies, humans' tactical genius would have led to the defeat of the "Fleet of Fog".

While battleship Hyuuga doesn't directly disagree with that, she mentions that originally, all "Fleet of Fog" vessels with sufficient computational power of their Union cores were to have Mental Models. However, for the reasons related to the Admiralty Code and its subsequent disappearance, the original activation of the vessels was incomplete and none possessed Mental Models during the Great Battle in 2039. Only much later, the Mental Models were rediscovered and re-integrated into the "Fleet of Fog".

Aside from promoting tactical thinking and mindful analysis of the past among the Union Cores of the "Fleet of Fog" vessels, Mental Models - mostly as a side-effect - also grant the vessels with additional means of communication and they also make it possible to infiltrate human settlements for reconnaissance or sabotage.

Common Appearance detailsEdit

While each Mental Model is unique, they all share some similar details in appearance. Namely, all Mental Models will have ship identification and fleet identification signs and the "Fleet of Fog" mark appear on their foreheads and the vessel's Union Core code mark appear on their left wrist when they are actively using their abilities as physical representations of vessels' Union Cores.

Also, wave-like marks will appear on the Mental Model's cheeks when she is connected to the quantum Joint Tactical Network of the "Fleet of Fog". Additionally, while such connection is active, the Mental Model's eyes will look digitized.


Mental Models, like everything else physical within the "Fleet of Fog" are made from the nanomaterials. This makes them extremely resistant to both attacks and physical impacts such as great accelerations. And even if the Mental Model becomes damaged in some way, as long as the Union Core of the vessel is safe, the Mental Model can be repaired and rebuilt. That aside, all Mental Models also have the following set of abilities:

Physical strengthEdit


Haruna's Mental Model ripping a tank apart with brute physical strength

It was shown throughout the series that Mental Models possess superhuman physical strength. Mental Models can perform great jumps that are far beyond anything human athletes can dream of. Takao was seen jumping from the levee to her ship body, easily covering the distance of at least 40 meters. Haruna was also seen being able to do such jumps. The Mental Model of battleship Haruna was also shown to able to physically rip a human tank apart, while Hyuuga's Mental Model could destroy a thick concrete wall with just two punches.

This superhuman physical strength also allows the Mental Models to move on their feet with the speeds of Olympic champions, even while carrying considerable extra weights on their persons. And as Mental Models are essentially machines, they will never tire out.

Wave-Force armorEdit


bullets and tank shell stopped by Haruna's Wave-Force armor

All Mental Models, even those whose ship-bodies were sunk or destroyed, still can use Wave-Force armor to protect themselves from enemy attacks or even to attack themselves. While, obviously, the Wave-Force armor of a Mental Model is weaker that that of a full vessel - both in the total amount of energy it can absorb and the maximal amount of energy in a single attack that can be absorbed - a Mental Model is still more or less invulnerable to anything that humans can dish out on them. Only heavy bombs, high-caliber artillery shells and high-power lasers have a chance to saturate the Mental Model's Wave-Force armor before it either withdraws or destroys the aggressor.

Aside from being an impenetrable shield for the Mental Models, their Wave-Force armor is also a way to attack. However, these attacks will all be applications of blunt force: pushing objects away from the Mental Model. That, however, doesn't mean that these attacks are weak as, theoretically, enough force to crush a tank can be applied. Additionally, a Mental Model may use her Wave-Force armor to push around objects such as grenades to attack her targets with.


Stemming from their nature as a construct made from nanomaterials, the ability of a limited shape-shifting is also something that Mental Models possess. However, most often this ability is used merely to alter their clothes or other similar relatively minor details.

List of known Mental ModelsEdit

In this section, the list of the Mental Models that have made their appearance in the series is presented. For convenience, the list is divided into sections by the vessel classes.

Superbattleships and Capital shipsEdit

  • Supreme flagship Yamato (twins)
  • "Scarlet Fleet" flagship Musashi
  • "Scapa Flow" Fleet flagship Bismarck (twins)

Battleships and BattlecruisersEdit

Assault and Suppression vesselsEdit

Heavy CruisersEdit



Other Appearances of Mental ModelsEdit


B-67 submarine / "Phantom"

While Mental Models are something that is the defining element of the "Aoki Hagane no Arpeggio" universe, they also 'appear' at least once outside of it.

Early in September 2013, Ark Performance group has designed a Mental Model for the fictional Soviet nuclear submarine B-67 from the American "Phantom" movie. Considering that this Mental Model has the "Fleet of Fog" signs incorporated into her design, she might have been *adopted* into the Fleet. That would make her the only vessel with the nuclear-powered prototype within the "Fleet of Fog".

This Mental Model appears as a white-haired green-eyed girl in her mid-teens, dressed into dark-gray fur hat, dark-gray over-cloak with white fur lining, short dark-gray dress with some white fur decor, knee-high dark-gray boots and red pants. She also wears a red rose on the front of her over-cloak.

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