Ki Energy (lit. "Spirit Energy"; also spelled “chi” or “qi”) is one of the most complex energies in the universe, yet one of the simplest to implement. Ki is present in all living beings but it is extremely rare to find someone who has even a novice’s control over the energy, much less a master. Even people like Raikou, who seem to have mastered ki in its entirety, have barely any understanding of its uses. Ki has a distinction with magic in that all the energy of ki comes from within the user’s own body, from the user’s life force.
Ki has many different physical appearances, ranging every color of the visible spectrum and even potentially being colorless or invisible. This, however, is all merely aesthetics, though some people believe a person’s aura color has a relation to their personality, skills, or physical attributes. Because ki actually life energy and not magic, unless someone is killed, it cannot be negated. Ki has no specific element and is more a physical attack than anything else, and if someone uses elemental attacks they say are based on ki, in actuality it is a form of magic, not ki. There is the potential that someone could drain the ki of other living creatures and kill them, but the instances of someone gaining skill over ki that advanced are incredibly rare and it would be easier to learn life draining magic.