Prime Field War

The was a war waged between "humanity" and "Prime Field Devices". It was started by humans in fear of the Prime Fields, who gained a will of their own, with the intention of bringing total genocide upon their own creations.

Events leading up to war
It all begun with the discovery of the Susano'o Unit, which allowed humanity to detect the Master Unit within the Boundary. It was a being of immense power, possessing the ability to activate Phenomena Interventions and capable of affecting space-time, in other words, a "god". However, after being observed through many points of view, it was realized that it was actually a creation and that it could be controlled like an object. The Takamagahara System was created in order to control its power and system, however it was flawed. While its duplicated system was capable of intervention that "rewound" the flow of time, it couldn't intervene upon the "possibilities" that compose the world, in other words, it was incapable of altering the "events". In order to obtain the missing component (the power to change "possibility" into reality - the Azure) and complete the system, many experiments were performed in order to contact the Master Unit. As the Master Unit responded only to objects with a human form, the Boundary Interface Prime Field Devices were made. The first one, later on dubbed as The Origin, managed to make contact with the Master Unit, becoming its "eye" and obtaining the power of an Observer. Along with the power of the "eye", the Prime Field Devices gained "souls" and self-awareness. Fearing that the will of mere "dolls" could alter the world, humanity, upon the advice of Clavis Alucard, created the Anti-Observer Weapon, Sealed Armament: Izayoi and destroyed their "eyes", afterwards throwing them into the Boundary. Among those thrown into the Boundary was the first Prime Field Device, which managed to make contact with the Master Unit once again.

The war
Humanity's fears grew even larger than before. They feared what could Origin, who now wielded the power of a "God", do to them for the atrocities and experiments they committed against her and her "sisters", thus humanity decide to perform total genocide upon them and the Prime Field Devices resisted in self-defense. However, the Prime Field Devices, along with the first one, all had the same "dream", they wished for their "souls" to be recognized as "individuals", as well they themselves seen as humans and be able to live a normal life. Yet, humans couldn't accept them as such, as Prime Field Devices had far superior physical abilities than them and the Origin even wielded "power of god", not to mention that humans couldn't remove their preconception that as human creations, they could be nothing more than "dolls".

The Prime Field Devices were more durable and had superior combat abilities than humans, what's more the first Prime Field Device had the power of phenomena intervention. On the other hand, humans were more numerous and, thanks to Clavi's advice, already had prepared special equipment that wasn't affected by phenomena intervention, the Izayoi. The war was brutal and humanity, thanks to Izayoi, was able to confront their enemy, however, it wasn't capable of neutralizing Prime Field Devices and humanity had started reaching its limit. They decided to use a "certain something" to mass-produce a self-observing weapon of mass destruction, basing it off the technique used in creation of Izayoi, it was later known as the Black Beast.

The Black Beast didn't discriminate between friend and foe, and simply devoured humans, Prime Field Devices, and everything it could alike, making a world with nothing left, a world of death. Thus the world had ended, however, this was in accordance with humanity's plan, as all they needed was to win. As long as they could obtain the Azure and complete the Takamagahara System, they would be able to "rebuild" everything and prevent the creation of Prime Field Devices, while still having the "power of god" in their grasp.

Aftermath
The basic principle behind the Takamagahara System is the continuation of a "human world" and when it was on the verge of obtaining the Azure, a miscalculation appeared in the system. The Origin had started "rebuilding" the world, what's more, even after being denied, her "sisters" slaughtered and destroyed, she still wished for a "human world". Even though the "form" was different, the desire for a "human world" was essentially the "same", so the Takamagahara System not only couldn't oppose it, but was even "used" instead. The "vessel" used to rebuild the world was the Embryo and as an immense amount of seithr was required to smelt it, the Black Beast was used as a catalyst, which possessed far more seithr than necessary, allowing for activation of a massive scale phenomena intervention. Thus, the world was rebuilt basing it off information from the world that was destroyed before.