Ki (Life Energy) is the latent, metaphysical energy that is generated from individuals whose physical forms are composed of either Kishi, Mana, Aether or Nether. Two distinct forms of Ki exist in The Universe; conventional Ki (referred to simply as Ki) which is the life-force all biological creatures made of Kishi and Mana and Divine Ki which belongs almost exclusively to deities who are manifested physical in forms composed of either Aether or Nether.
The amount of Ki an individual possesses tangibly in their body is dependent on the physical condition of their body so physical training is a necessity to increase the strength and vitality of one’s body in order to make efficient use of Ki. It can be expelled from the body at will and manipulated when the proper training has been performed and can either be focused into directional energy waves or re-absorbed into the body to actively enhance the user’s physical condition for a temporary amount of time. Since the amount of Ki one can use is dependent on the user’s vitality then suffering from illness or sustaining serious injury can drastically lower the amount of the Ki that can be utilized.
Ki as an energy source can be manipulated in many other ways other than the aforementioned energy waves and the full extent of the properties and specific manipulations of Ki have yet to be discovered - though it has several practical uses such as igniting fires and generating light.
There are certain requirements that exist for an individual's physical form to possess Ki.
- The body needs to be composed of Kishi (Corporeal Particles) meaning that Spiritual Entities composed of Reishi are unable to generate Ki by any means.
- The body needs to be both biological in nature, and alive with Reiryoku present in the body. This prevents Undead or Artificial Intelligences from possessing any Ki, even if they utilize a biological form because spiritual energy is required to be inside the body which machines lack. Biomechanical Androids however - so long as they possess a Soul - can generate Ki.
- The only exception to both of these requirements for generating Ki is the unique species called the Majin; beings composed entirely of Mana. This exception is generally regarded to be due to the mystical and unstable nature of Mana allowing it to mimic biological life.
Deities do not typically possess a standard, physical form but when they create an Avatar composed of Aether they produce a variation of Ki which transcends conventional Ki in scale and effectiveness. Only other individuals with Divine Ki can use Ki Sensing to locate a source of Divine Ki.
Aside from this imperceptibility Divine Ki is functionally identical to standard Ki - it also has similarities to Transcendental Reiryoku in being both imperceptible to lower entities and generated by deities.