The Counter Force (抑止力, Yokushi-ryoku?, "Deterrent Force") is a safety device formed by a World to defend itself against extinction and is synonymous with the World it represents.
The concept of Counter Force is central to the world, and there are two types: Gaia and Alaya. Gaia is the will of the Earth, the planet's intrinsic wish to survive and prosper. Alaya, on the other hand, is the collective unconscious will of mankind to avoid extinction. As humans are creatures of Earth, Alaya was a component of Gaia. However, as mankind began to develop independent from nature, it became independent. With this divergence, Alaya is no longer aligned with Gaia and potential conflict can result.
Despite being called "the will of the planet/mankind", the Counter Forces bear no emotions. They are described as passive spirals of energy that respond to threats of planet destruction or human extinction. The Counter Forces are always active, constantly steering mankind and the planet away from potential danger. Usually, the Counter Forces act indirectly. For instance, Shiki Ryougi was driven by the Counter Force to eliminate the threat that is Souren Araya, while Jeanne d'Arc is believed by Mikiya Kokutou to have possibly been empowered by the Counter Force. One exception to this is Enkidu, who is able to access the Counter Force directly through their Noble Phantasm, Enuma Elish.
Although Gaia and Alaya are intangible forces of will, each does enlist physical agents to deal with events too threatening to address with indirect intervention. The agents of Gaia consist of the Elementals such as: Lugh Beowulf, Fairies, True Ancestors, some Phantasmal Species, and some Divine Spirits. The agents of Alaya are Heroic Spirits and the Counter Guardians, human spirits who pledge their eternal service to Alaya in return for power during their lifetime.
The Counter Forces have immense power at their disposal. However, only the appropriate amount is unleashed to address a particular event. If the threat possesses an amount of power equal to X, then the Counter Force will deploy an amount of power just enough to snuff out X and eliminate the threat. The amount of power can be as small as nudging individuals into place through "coincidences", but it can also be as great as sinking an entire continent.
According to Merlin in Garden of Avalon, Counter Force is a defensive mechanism born of the collective unconscious of mankind, and that the difference between the Heroic Spirits and the Counter Guardians of Counter Force is that the Heroic Spirits are summoned by the hopes of men, while Counter Guardians are summoned by the despair of men.
Alaya (アラヤ, Araya?) is the collective unconsciousness of mankind and the drive for its survival as a whole. Alaya constantly steers mankind away from extinction.
Usually, Alaya interferes indirectly by guiding and empowering an individual to eliminate a threat. Such individuals include Shiki Ryougi and nearby individuals. When indirect intervention is insufficient, Alaya will deploy the Counter Guardians or Heroic Spirits. The deployment of Counter Guardians is by no means subtle, as the threat will be eliminated with the surroundings, inflicting much collateral damage. Touko Aozaki hinted that the sinking of Atlantis was the work of Alaya, though her theory was actually incorrect, as Atlantis was orignally destroyed by Sefar.
Alaya is of particular relevance to magi, as those close to reaching the Root are deemed threatening by Alaya. Many of them go to extreme lengths to avoid or hide from Alaya. For instance, Araya Souren attempted to hide his approach to the Root by containing his experiment in a boundary field close to a Reality Marble, essentially masking his work by internalizing it.
Human Order (人理, Jinri?), also referred to as the Common Sense of Man (人理, Jinri?, lit. "Human Principle"), is the core principle on which Alaya operates for the building of the Human Order Foundation. Essentially, it is the principle that "humanity must exist for as long as possible." Parallel worlds in which humanity has destroyed itself or advanced too quickly and therefore stopped progressing are, following this principle, culled, allowing for only the most promising parallel worlds to survive in order to ensure the future of mankind. Should it be overturned or compromised as it was by Goetia, the fabric of time would fall apart and humanity would be doomed.
Gaia (ガイア?) is the planet's will to survive. Gaia protects all creatures on Earth by using Nature Spirits and creatures of the Earth, but as mankind becomes independent, Gaia increasingly perceives humans as a source of threat due to their reckless destruction of the environment.
Gaia's response to the human threat is producing beings that can cull or rule mankind. Primate Murder was created to quickly eliminate humans. The True Ancestors are great Faeries modelled after the Crimson Moon, introduced by Gaia to rule over mankind.
The destruction of the planet by Earth-born creatures is essentially impossible due to measures already put in place by the Counter Force. Even Anti-Planet Noble Phantasms are unable to accomplish this feat.
Counter Force of Alaya
- Main article: Counter Guardian
Monster of Alaya
The Monster of Alaya (アラヤの怪物?) is unidentified.
Within the Garden of Order Singularity, there appear ghosts that are described as "defective Monsters of Alaya," representing the "ultimate form of someone who absolutely hates humans." They are described as "Innocent Monsters with super-recovery, super-stamina, and super-skills." They are nameless creatures who appear to be reaching a state similar to that of Primate Murder, that which can reliably kill any primate species.
Counter Force of Gaia
Monster of Gaia
Within the world of Fate/kaleid liner PRISMA☆ILLYA, Tanaka is a manifestation of Gaia, serving as its Counter Guardian in the face of the overwhelming threat of the "corrosion of the world on the other side of the hole". While she entrusts the fate of the planet to Illya, as a terminal for Gaia, Tanaka is ultimately indifferent to the survival of humanity itself.
 Kara no Kyoukai Special Pamphlet - Encyclopedia: Counter Force [Others], p.041-042 [T]
Counter Force [Others]
The Counter Force here is the safety device formed by the collective unconsciousness.
The prayer to avert the demise of mankind, Alaya.
And the prayer to extend the life of the planet, Gaia.
These are the two aspect of the Counter Force.
Both aspects have the goal of extending the existence of the current World. They will eradicate the factors that threaten to destroy the World at the moment of their occurance.
Since the Counter Force is the unconscious, its appearance draws no attention, and no one will recognize it.
The Counter Force is a formless spiral of power. It adjusts its scale based on the target that needs to be obliterated. The Counter Force will always appear with a status above the target, enough to absolutely secure a victory.
Normally, the Counter Force empowers "a normal person" to remove the factor that can trigger destruction. As a result, these individuals are worshiped as "Heroes".
Individuals who became Heroes through the aspect of Alaya are said to be integrated into Alaya after death. However, the accuracy of this statement is uncertain.
These individuals are also called Counter Guardians. The emphasis here is "Counter", because they have no autonomy and will only activate in response to an event.
 Fate/EXTELLA Material - Quantum Time-Lock
Quantum Time-lock [Existence]
Spiritron Record Anchoring Bands (霊子記録固定帯, Reishi Kiroku Kotei-tai).
An event that manifests at regular intervals for the purpose of anchoring the Average Expression (平均値, heikin-chi?, lit. "Average Values") of phenomena as absolutes.
This universe permits the birth of unlimited possibilities, numerous adjacent worlds, and divergent developments of history.
However, as the unrestricted propagation of this process would exhaust the lifespan of the universe, at set intervals, those extraneous worlds (世界, sekai?) removed of the category of "routes characterized by survivability and stability" are culled (伐採, basai, lit. "cull" / "prune"), so as to prevent the needless expenditure of energy.
The Mooncell has concluded that the means by which our Universe of Awareness (認識宇宙) -- fundamentally unstable by nature -- is stabilized across the Past, Present, and Future lie in the execution of "culling" and the formation of "records" (記録帯, Kiroku-tai, lit. "Recording Bands").
If left alone, the Great Tree Known as Time (時間という大樹, Jikan to Iu Daiju?) will branch without restriction, and the behavior of culling serves to remove those divergences that are unnecessary, leaving only the "trunk" to advance. This is the simplest image by which to comprehend the phenomena.
Any history that has been secured as an anchoring band (固定帯, kotei-tai) become as an existence impervious to interference from the past and future; events or phenomena that exist within the purview of the anchoring band are utterly immovable.
Hypothetically, if one were to move to a chronological position in the past of an "anchoring band" to the purpose of modifying history, as time progresses unto the position of the "anchoring band," history would be forcibly corrected (強引に復元, gouin ni fukugen?, lit. "forcibly restored") to its state of record.
In those universes wherein Quantum Time-Locks are imposed, the "outcomes" that have been registered to anchoring bands are categorically unchangeable. Thus, that which would be open for time travelers to modify would be invariably restricted to "process."
For example, let us presume that the "outcome" that "Britain was destroyed" is secured as a matter of record.
In the circumstance that a process wherein "Britain comes to prosper; its wars are concluded; and happiness is granted to its people" is successfully brought about, in the moment that history advances unto the anchoring band, the outcome whereby "even so, Britain came unto its destruction" manifests.
One or two -- or any number of lives might be saved.
However, modification to the overall course of the History of Man (人類史, Jinrui-shi) is decisively beyond possibility.
These are the Quantum Time-Locks -- those existences referred to within Thaumaturgical Society as Human Order Foundations (人理定礎, Jinri Teiso?, lit. "Foundations of the Rationality of Man").
To rephrase, it is potentially possible that by some immense undertaking, the course of the History of Man could be fundamentally denied by successful revocation (破壊, hakai, destruction) of a "Quantum Time-Lock," but even by this method, that which is denied is restricted to "the History of Man that falls subsequent to the anchoring band."
The purview of a "Quantum Time-Lock" due to manifest may be dictated only those who live within the era. Intervention from the past or future is incapable of directly influencing the formation of a Quantum Time-Lock.
 Fate/EXTELLA - Chapter Altera - Prologue
Upon the Earth, there is exists the hypothesis of "Adjacent Worlds."
The World is not one; rather, like a reflection in a pair of opposing mirrors, it infinitely unfolds. Consequently, there cannot exist only a single future -- or so it's thought. In other words --
Let's explain it like this. The you that exists right now can be described as a you that exists somewhere within this flow of time.
It's probably difficult for you to envision. After all, it's impossible for humans to even perceive "the Boundaries Between Worlds" (世界の壁, Sekai no Kabe?) -- much less what lies beyond.
So, how about I rephrase? Worlds that run adjacent are essentially as "possibilities."
Conclusions that may be possible.
Bonds that were abandoned.
Options that went unnoticed.
Divergent futures, wherein "what ifs" such as these were permitted. It is indeed these "realities in which the future was altered" that are referred to as Adjacent Worlds.
The you who is now alive --
By the actions of the you who exists here and now, the course of the World can shift in any number of ways.
This is proof that "possibility" (可能性, kanousei?) is itself still alive; positive evidence that your World still lies upon its "proper axis" (正しい軸, Tadashii Jiku?).
In converse: For those Worlds wherein the act of choice can no longer impact the future, Adjacent Realities cannot exist.
Such timelines merely advance.
Losing even the possibility of undoing the past, they become distinct, solitary Worlds.
Their manifestation is a necessary evil, structurally mandated.
In those worlds where choiceless choices incessantly persist, the form of the "World" familiar to you cannot endure.
There should exist worlds ruined by the repetition of choices in mortal error, yes?
There should exist worlds that excessively advanced their civilization by way of continuous innovation, yes?
But once a World arrives at such a state, it can no longer be counted as "a World comparable to the others" (他と同じ世界, hoka to onaji sekai?). If the Foundation of a World (世界の基盤, Sekai no Kiban?) has deviated, it becomes that which is known as an Otherworld (別世界, Betsu-Sekai?, lit. "distinct reality").
But why do such realities become solitary? Shouldn't it be that whatever the future, the possibility of adjacent advancement persists?
Unfortunately, this isn't the case. The energy to account for the proliferation of unnecessary worlds, exists nowhere within this Dimension (次元, Jigen?).
That is to say, the ceaseless proliferation of Adjacent Realities may eventually exceed the capacity of the Dimension as a whole.
Adjacent Realities are a necessary existence, but they cannot be let to freely multiply.
It's a very rough estimation, but should the Earth persist at its present level of civilization for another century, it's likely that the Solar System will collapse.
However, the reality is that we live and multiply. The Solar System hasn't yet dissolved (緩和, kanwa?, lit. "loosen / relax / alleviate") before the sheer volume of data that we produce, and it's likely that the status quo (今の方式, ima no houshiki, lit. "the present formulation / system"?) can be sustained for another hundred million years.
And the principle behind it is simple. To a certain extent, the existence known as the World (世界という者, Sekai to Iu Mono?, lit. "the thing called the World") conducts a hueristic analysis (統計, toukei?) of timeline survivability (進むと可能性, susumu to kanousei?, lit. "prospects and potential"), preserving only those Outcomes wherein "the operation of the subsequent era" (次の時代の運営, Tsugi no Jidai no Unei?) isn't impossible.
For those Adjacent Realities judged to be unnecessary -- the future is closed.
In more concrete terms, cumulative audits (集計, Shukei?) are conducted at intervals of a century in scale (百年単位, hyakunen tan'i?, lit. "units of a century"), to the end of identifying and preserving only the possibilities (可能性, kanousei?) of those Worlds capable of guaranteeing "the preservation of capacity for advancement in yet a subsequent century, at bare minimum."
Per the systematic demands (法則, housoku?, lit. "laws") that facilitate the Conservation of Mass (質量保存, Shitsuryou Hozon?), this process could be termed the Conservation of Phenomena (事象保存, Jijou Hozon?).
Thusly, the civilizations of the many extant Adjacent Realities largely refrain from divergence. You can imagine it as a great tree. The worlds permitted to advance are restricted to the center -- comprising the trunk. Those branches that diverge grow and multiply, but eventually succumb to their limitations (限界, genkai?), falling to ruin without reaching a future.
You understand, yes?
Those worlds that advance too far into ruin or prosperity are bankrupt of Adjacent Realities (平行世界, heikou sekai?). Otherworlds (異世界, Isekai?) such as these are little more than blind alleys (袋小路, fukurou-kouji?) whose outcomes are foreordained.
The time of the culling brings a termination to unnecessary possibilities -- the point at which, by force of Observation (観測, Kansoku?), the mutable Histories of the past solidify as a static course.
This is what the Magi of the Old World (旧世界, Kyuusekai?) referred to as Phenomenon Anchoring Bands (事象固定帯, Jijou Kotei-Tai?) -- the Foundations of the Rationalities of Man (人理定礎, Jinri Teiso?).
 Fate/EXTELLA - Chapter Altera (Localization) - Prologue
"Earth scientists have hypothesized the so-called 'parallel worlds,' other versions of Earth and its surroundings, expanding indefinitely like mirrored reflections. If true, that would mean that Earth has not only one future, but many. In other words ..."
"Think of it like this. The 'you' that you are aware of exists somewhere upon this timeline."
"It might sound unreal. Humans aren't equipped to perceive, let alone traverse, the 'wall between worlds.' But what if I put it another way? Think of these parallel worlds as other possibilities."
"Imagine what might have been in your life. Think of the connections that were cut off and thrown away. Options you see now, in retrospect, that yu would never have considered at the time. Picture how your life today might be different had those 'what ifs' come to pass. All those variant futures, in everyone's lives, make up the vast array of parallel worlds."
"Your actions, those of the 'you' in this present moment on this particular timeline, can change the world in any number of ways. That proves such possibilities are alive, and that your world exists on the 'proper axis.'"
"Conversely, a world where the future cannot be changed, regardless of your choices, can have no parallel worlds. Such a world is nothing but a dead end, solitary and singular, with a past as immutable as its future."
"This is a necessary evil, a byproduct of the way parallel worlds are structured together. After all, a world where humanity made radically different choices would bear very little resemblance to the world you know."
"Some worlds may have crumbled by making all the worse choices. Others may have made all the right ones, and rocketed ahead, perhaps too far ahead. In either case, that world can no longer be said to resemble ours, and once a world moves out of sync, it is no longer 'parallel.'"
"'Why would those worlds become solitary,' you ask? 'Could the people in those worlds not still make different choices?'"
"Unfortunately, no. This dimension contains a finite amount of energy, and has none to spare for creating new worlds from the worlds gone so far astray."
"If parallel worlds continued to increase in this manner, their number would eventuallky exceed the capacity of this dimension. Parallel worlds must exust, but in a manageable quantity. By my own rough calculations, and judging by the civilization of Earth alone, this solar system would collapse within 100 years if parallel worlds expanded without limits."
"Seeing as how we do, in fact, live and multiply, the solar system is clearly not oversaturated with possibilities at this time, I extrapolate that this dimension can sustain our existence for the next 100,000,000 years."
"The system works thusly: At regular intervals, the dimension takes stock of the possibilities it contains, and only allows certain outcomes, those that would not cause undue difficulty in managing the next generation, to remain. As for the unneeded parallel worlds, the system closes off their futures."
"Specifically, every 100 years, it calculates how many worlds will last another 100 years, and supports those worlds only. Have you heard of the Law of Conservation of Mass? This could be called the Law of Conservation of Events."
"And so, the civilization in these numerous parallel worlds line up with one another. Think of it all as a giant tree. Only the trunk at the center can grow tall. The branches may bear fruit, but eventually they reach their limit, and fall without reaching the future."
"You understand, yes? There are no parallel worlds for a world that has evolved too fast or crumbled too quickly. Such worlds are merely dead ends whose outcomes are predetermined."
"And so, there is a set time frame in which these branches are trimmed, extra possibilities are removed, and future histories, once fluid, turn to stone. The mages of the old world called this time frame 'the Foundation of Humanity.'"
- Fate/Grand Order Shinjuku Singularity: Chapter 11 story summary translated by Aesma-Daeva.
- Fate/Grand Order - The Garden of sinners - the Garden of Order - Into the Woods