Amenokai

The  (天の界, Celestial Kingdom), also referred to as the Upper Planes and the Celestial Planes respectively, was a term used to describe the plane of existence belonging to the Tenjin, a race of God-like beings that came into existence at the dawn of time and creation, having emerged from the Pre-Universe to the Current Universe through a space-time tear called the Shussho.

The Amenokai was composed entirely of pure Chiryoku, the Primordial Energy of the Universe, and the lifeblood of God-like beings such as the Tenjin and the Ki-Rin. It was said the reach of the Amenokai was nigh infinite, and in a sense was true as one can simply walk to the edge of the horizon yet never reach an end. As a result, the full extent of the Amenokai could never fully be mapped.

It was said there was an infinite number of domains within the Amenokai, with thousands of them yet to be found or created. In particular, it was widely assumed that every Tenjin that ever existed ruled over a particular domain of their own design within the Amenokai. Even if the Tenjin was killed and ceased to exist, their domain would still continue to exist but remain unreachable. The domains of the Tenjin were believed to be a reflection of their personality and predisposition, and could change at a moment's notice.

Creation
Before the Amenokai was the Void, a seemingly vast and empty ocean of nothingness, devoid of light and darkness. It remained empty until a God-like species called the Greater Tenjin arrived from places unknown. Legend has it that the Greater Tenjin were purportedly survivors of the Pre-Universe who managed to escape destruction wrought by an apocalyptic phenomenon called the Universe Reset, which essentially destroyed all that once was to start everything anew. The Greater Tenjin arrived in the Current Universe through a space-time tear called the Shussho (出所, The Birthplace). To their surprise, the Greater Tenjin were blessed with the cumulative power and energy of the Pre-Universe, which they began to call Chiryoku. Using Chiryoku, the Greater Tenjin forcibly molded the Void around the Shussho into what was now known as the Amenokai, a vast, malleable plane of existence that answered to their every whim.

With their now immortal bodies, the Greater Tenjin began to reproduce at an extraordinary rate, producing thousands of children that they referred to as the Lesser Tenjin. With the birth of the Lesser Tenjin at hand, the Amenokai began to unconsciously respond to the Lesser Tenjins' subconscious, forming a personal domain for each of them, which numbered in the thousands. When the Lesser Tenjin became self-aware and independent, they ultimately rebelled against the Greater Tenjin, sealing them within the heart of the Shussho at the expense of the majority of their kindred. Those who had perished later became one with the Amenokai in the form of Chiryoku, serving as the very life fuel for their kind.

Rulers and Inhabitants
All Domains found within the Amenokai were either ruled by a Tenjin or at least associated with them one way or the other.

Interactions with the Lower Plane
The Lower Plane was a collective term used to describe dimensions existing outside the domain of the Amenokai. These dimensions were primarily created by the Tenjin in their desire to create mortal life. The most well known Tenjin who dabbled in this endeavor was the Lesser Tenjin known as. The Balancer was responsible for the creation of the, , , , and the. On the other hand, the realms of Kōhai Tochi and Heisekai were created by The Builder and The Engineer. The Amenokai remained hidden from the Lower Plane and could never be fully detected by even the most powerful of sensors. The existence of the Amenokai was only hinted at by the existence of the himself and the sparsely recorded interactions between Ikusa and his Yuengiri followers. Even the highest echelons of and Heisekai remained largely unaware of the Amenokai, although they could had chosen to not acknowledge a greater power than themselves.

Travel between the Lower Realm and the Amenokai was made possible with the creation of the Spiritual Roads, stable and permanent pathways of Chiryoku that guided the residents of the Amenokai to their chosen destinations. All Spiritual Roads were connected to the, which secretly served as the central hub of the Roads. While the Shinigami believed they had fully mapped the entirety of the Dangai, that notion was false. The Lower Plane Inhabitants (Shinigami included) only had partial access to the Dangai and were unaware of the Road Hub's existence.

Domains in Amenokai

 * Shussho
 * Tougenkyou
 * Hall of the Reaper
 * Blissful Gardens
 * Factory of Innovation

Trivia

 * Like with all Tenjin, The Outsider likely possessed a domain of his own. However, it was never shown or referenced, largely due to The Outsider's constant travel between other dimensions. As revealed by APS, it was called The Outskirts.

Behind the Scenes

 * The idea of a "Pre-Universe", the existing reality before the Current Universe, was based on Earth-0, the previous reality before the main reality known as Earth-616 that was found within Marvel Comics.
 * The Universe Reset was based on the Cyclic Model concept, one of several cosmological models that revolved around the theory that the universe follows infinite, or indefinite, self-sustaining cycles.