Junshū

Junshū (准州, Territory) is a magic-esque ability born in Plus souls, akin to that of human extrasensory perception, after being subjected to reiatsu by Shinigami who remain near them over long periods of time. Essentially, they become "Pseudo-Shinigami".

It has been addressed as Territorio (テリトリー, teritorīo; Italian for "Territory") by those among Impero Nascosto.

Overview
Kamui commented that Junshū is a strange power in that it does not rely on a "system", nor does it follow the laws of a system. In this idea, it truly is a "magic" ability, and is considered similar to that of Kidō; ironic, considering that Junshū users are considered "Pseudo-Shinigami". In addition, the way it manifests is completely unique to the emotional nature of its host. The reason only souls, and not actual humans, are able to awaken this ability is because of their anatomy. Humans have material bodies composed of atoms while soul bodies (such as Pluses, Shinigami, Hollows, etc) are composed of reishi. Matter, over a long period of time, will eventually fade away due to extended exposure to reiatsu. This is because material bodies composed of matter acts as a "barrier" to the reiatsu being "pushed out" by the human's soul. Normally, a human's spiritual power is too weak for it to do so and the reiatsu exerted by their internal soul is not very effective. Hence, it takes decades for the reiatsu within the material body to cause the aforementioned atom-composed body to die (which is the cause of aging itself in the material world). Those with ESP, however, die much quicker because their spiritual energy was, at birth, considerably higher. Souls that have bodies composed of reishi are not subject to this, and their reiatsu is exerted outwards without fear. Junshū users are those who have the capabilities of becoming Shinigami, but never went through formal training, and eventually their powers awoke in a different manner altogether due to continued exposure to higher amounts of reiatsu.

Junshū, at its most fundamental nature, is "giving a soul's reiatsu a physical form". As its name implies, it relies on the user enacting their "territory", which is the range of their reiatsu. Within this territory, the possibilities they can preform are never-ending so long as they all connect to the nature of their unique Junshū. For example, if one's nature is in linguistics, their Junshū may manifest as an ability to make certain words or letters forbidden, and those who utter those words or letters will be inflicted a form of punishment that is based on the rules set up by the Junshū user. Ideally, within their territory, they are a "God".

Due to the possibility of their abilities allowing regular souls to overpower the Shinigami, because of their never-ending possibilities and versatility, the Shinigami eventually enacted Shinigami Executive Order Fifty-One, which ordered all Captains of the Gotei 13 to seek out all Junshū users and eliminate them. Very few escaped this massacre, and those that did, went into hiding.

Inside & Outside Territory
There exists two primary ways for an individual to gain Junshū powers, and each method leads to which type of Junshū they develop.
 * Inside Junshū: This is obtained over time by souls that engage in deep martial arts training. Martial arts is the way of being at peace with the spiritual, and the ultimate goal of martial artists is to be able to harness pure energy at its core. Ideally, their "territory" is their own bodies, and that they can control aspects of their body and produce effects that would normally be considered utterly impossible (except for Grandmaster-level Hakuda masters, such as Seireitou Kawahiru). Those that develop Inside Junshū typically produce energy-style techniques, akin to that of Getsuga Tenshō, but those who truly become proficient at it can find many other uses for it. However, those who can use Inside Junshū are extremely rare, and only a handful of them exist, due to the demands that martial arts itself requires. Souls that gain this power no longer release a spiritual pressure, meaning that one will not be able to sense their presence.
 * Outside Junshū: The most common form of Junshū, it is a power where those who utilize Junshū can enact their "territory" around an area of their choosing. Within this area, they are a "God", and decide the rules of that territory so long as it connects with their unique Junshū ability. The range of one's Outside Junshū is proportional to their reiatsu range, with more experienced users having far-extending reaches. Within the territory, they decide the rules and everyone in it must play by those rules. Those who fail to do so are inflicted punishment as decided by the user. The effects of those who lose in one's territory remain on them even after the territory is released and can only be negated by the Junshū user who inflicted said effect. When one is capable of defeating the user (meaning that they have caused the Junshū user to lose at their own rules), then all effects set upon by that Junshū user within a particular amount of time prior to the victory are negated. An example is, if the user decides that "violence" cannot occur within the territory, then even someone who possessed immense physical power is essentially powerless. The only real way to defeat an Outside Junshū is to beat the user at their own rules. As god-like the power may be, there are limits to what a particular Junshū's rules can be set, as they all must remain consistent with the nature of the Junshū user.

Behind the Scenes
This article is based on the Psychic powers developed by some humans in the Yu Yu Hakusho manga series. In addition, the concept of Shinigami using "inside power" and Quincy using "outside powers", as stated by Uryū Ishida, also led to the creation of which individuals can develop one method or the other.