Spiritual Force

Spiritual Force (霊勢威, Reiseī), not to be confused with or, is a metaphysical energy source, similar, but not the same as spiritual energy. Unlike, which only compose spiritual beings and structures, reiseī can be found in the cells of every single being, sentient or not. Sōsuke Aizen explains that, despite this fact, it is impossible for even beings with spiritual awareness to utilize it without an outside force acting on it first. He goes on to explain that the Hōgyoku is one of the only objects that can awaken this ability, though even by this method, the results are random. These facts aside, a clan of (similarly to the ) are naturally born with these abilities, though they are extraordinarily rare.

Overview
Spirit force is in ever living creature, be they sentient or not, although in very small amounts. If acted upon by a special force, such as the Hōgyoku, the concentration of these particles increases to insane amounts, giving the user superhuman abilities far beyond that of an average Shinigami. Once a person became able to use spiritual force, they gained mental-based powers that go far beyond the average telekinesis; the only limitations to its abilities seem to be in the imagination of the user and the concentration of reiseī particles in their blood.

Spirit force has been shown to conjure powers that resemble ' and ', but seem to be stronger, depending on the user. The user can also boost their physical abilities much higher than that of an average Human, allowing them, for example, to jump higher and stay in the air longer, or to run at speeds that rival that of techniques. Reiseī-users often use their powers to alter or mess with their natural environment, such as channeling a lightning bolt into their foe or targets. It is also an effective agent for healing. The use of spirit force is unique among the various sources of a spiritual being's energy in that its nature is affected by the morality of the person wielding it; for example, those users that are evil affect their spirit force in such a way that it becomes more violent upon use, while those who are good in nature tend to have stronger affinity in protecting themselves and the ones they love with the power. It can also be effected by intense emotions, even activating itself unintentionally, in the case of Shōgi Kudō when he had become mentally enraged and grieved over the revelation of his past.

Spirit force is also not limited to use of one's own, as users can also use outside spirit force by gathering and channeling it into their bodies, which can make their supply of it seem near limitless.

Despite its seemingly limitless possibilities, use of spirit force does come with its own significant weaknesses. If a being uses it beyond their body's limits (determined by the concentration of particles in their blood cells) to sustain it, that person could suffer physical damage and dermatitides, accelerated aging, or, in extreme cases, vaporizing themselves by literally burning their cells up.

Spiritual Force Levels
Each of the "levels" of Spiritual Force denotes control of the ability, as well as the approximate level of reiseī in that persons blood.

Spiritual Force
This level denotes the average user of spiritual force, who have a concentration of reiseī particles that are near, but slightly greater, than Human-level, giving them some abilities. The vast majority of beings that actually obtain spiritual force fall under this category.

Adept Spiritual Force
This level of control corresponds to those that possess a high concentration of reiseī particles in their blood. Unusually, beings that obtain usage unnaturally, with objects like the Hōgyoku, remain in this level of power. For all of his skill, even Sōsuke Aizen, who had gained Spiritual Force through use of the Hōgyoku, admitted that even he could not rise above this level. Despite this, users that reach this level are immensely powerful and can easily outclass Shinigami captains and their counterparts in the Royal Guard.

Vast Spiritual Force
A very rare level, used to denote those that are immensely talented in the use of Spiritual Force. The only known user at this level is Shōgi Kudō, which may be due in part to the fact that he's a cloned being who has had his cells messed with numerous times. Users at this level are denoted to have the most extraordinary powers, being able to pull superstructures from the sky, redirect lightning bolts, and influence the environment with their mere emotions.