Jiseiryū

Jiseiryū (自制流, "Self-Control Method"; literally "Art of Controlling One's Self") is an advanced skill that had been mastered by the w:c:bleach:Shinigami, which allows them to manipulate the core of their bodies: the reishi that composes their being. It serves as the foundation and most basic principle of Seireitou Kawahiru's Reishūha technique.

Overview
In the most simplest way of understanding, Jiseiryū is a skill present in all martial arts and refers to the act of controlling one's body to the point of executing one's techniques in a refined and precise manner. However, martial artists do not classify this as its own skill, but rather a way of behaving; a way of living one's life through self-discipline. This is because, to them, the act of Jiseiryū is a purely emotional command of one's mental faculties. While these are the core teachings of Jiseiryū, it is not even close to the truest expression of the skill.

Spiritual beings, such as the Shinigami, utilize the true nature of Jiseiryū by learning to manipulate the very reishi that compose their being. In doing so, they access a variety of feats otherwise deemed impossible. The most notable cases of Jiseiryū were developed as a means of gaining greater command over one's Zanpakutō.


 * Genryūsai Shigekuni Yamamoto, whose Bankai, Zanka no Tachi, generates flames so immense that they reach temperatures rivaling the Sun itself. In any normal case, such heat would incinerate a being upon mere initial contact; not even that. By mastering Jiseiryū, Yamamoto had mastered the art of using his Bankai to the point of actually wearing its incredibly intense flames as a sort of armor over his being; a feat originally considered to be impossible.


 * Rukia Kuchiki, whose Shikai and Bankai, Sode no Shirayuki and Hakka no Togame respectively, has the extreme opposite power of lowering Rukia's body temperature as well as the surroundings to absolute zero. At such a temperature, the laws of physics demand that no life and subsequently that all motion ceases to exist, due to there being a theoretical zero amount of energy present. However, through strength of will, the Jiseiryū allows her to move even while in this state. However, her control over the technique is still amaterish at best and thus, she is only capable of four seconds of free movement before being unable to act, lest she suffer damage at the hands of her own Zanpakutō. Rukia noted that the Jiseiryū essentially allows her to "fight in a state of death".

Known Users

 * Seireitou Kawahiru - mastered the Jiseiryū and acheived the highest level of Hakuda.
 * Genryūsai Shigekuni Yamamoto - mastered the Jiseiryū, allowing him to wear the flames of his Bankai.
 * Ichibei Hyōsube - known to have taught Rukia the technique.
 * Rukia Kuchiki - was taught the Jiseiryū by Ichibei, which allowed her to gain temporary movement in her "absolute zero" Shikai and Bankai states.

Behind the Scenes
This article is meant to expand on a brief concept brought up by Kubo.