Kairyū

The Kairyū (界流, "World Flow") is the cycle of energy that permeates throughout every realm and dimension of space and time. It is a binding and ubiquitous energy that connects all things and is the foundation of all natural things in the universe. It is the source of life and allows for the traffic of souls to exist.

Connection with Combat
Through the idea of, it is said that each of the four fields of spiritual combat deal with the Kairyū in one way or another. In, the practitioner taps into the Kairyū in order to draw energy for the sake of utilizing magic in the form of various spells. In, the practitioner goes through training to first mimic the power of the Kairyū, through the study of nature and observation of the world around them, turning it into their own, and eventually surpass it as they manage to reach a precipice all their own. In, just as the swordsman and their blade must connect, so too does the practitioner manage to connect with the Kairyū. In, the practitioner uses the Kairyū as a sort of map or "guideline" in which they develop their movement techniques. These four — controlling, becoming, cooperating, and following — are the four fundamental methods in which one can utilize the Kairyū to benefit their combat abilities.

Kairyū-Borne
There is a rare phenomenon that occurs every so often in which the Kairyū accumulates in a certain locale and manages to manifest as a personification of the world flow itself. This is known as a Kikkyōhen, or "Anomaly of Karma", and they are an existence outside of the traffic of souls. In other words, they are outside the realm of life and death. is an example of such a being.

Behind the Scenes
While the concept of a "world flow" exists in many fields, one of the primary sources of inspiration for this article came from the idea of Altana from the manga and anime series, Gintama.