Kiai Do means Way "Do" of "Ai" controlling, harmonizing and balancing Universal Energy "Ki"

Kiai Do is an art that employs sound, it works at the energetic level using sound as a tool to affect your own or other's energetic field. Although commonly the Kiai is considered a shout, it is much more, notice that Aiki-Do is written using the same characters of Kiai-Do.
Ki is a Prana: Chi, Qi, Ki, life energy, breath. In living it always refers to breathing that is a model of all processes in the Universe: creation and destruction. Every breath is a natural flow of energy which contains all the information of the outside world (Universe) during inspiration and all our internal information in expiration. The training makes it possible to activate a specific inspiration, transforming it into a source of strength and wisdom, while the exhalation can be charged and focused in order to be effective for health, combat, pleasure, understanding, etc..
Ai means "union", concentration, but also to direct, to govern, to lead, to control, to harmonize, to synchronize, etc..
Therefore, training Kiai-jitsu (Kiai technique) is to develop the ability to handle the breath combined with all the methods of application of sound, including the Kiai.

The Art of Kiai (Energy of the Sound of the voice) is used for both healing and martial arts.  It is a main foundation of the Art of Kiaido – the Way of the Warrior-Healer.  It integrates and unifies Martial and Healing Arts into one integrated system.

On the healing side of Kiaido training (Jindo) one practices movements, breathing exercises similar to those of Yoga and Tai Chi/Qi Gong practices.  However in Kiaido all exercises are accompanied by the sound produced by voice of the Kiaido practitioner, which enhances the breathing and activates and regulates all energy and elements of the body through simple, easy and effective methods, that yields quick response of the body.

On the martial side of Kiaido, Kiai Jitsu Fighting Method combines Kyusho Jitsu (Dim-Mak) – Pressure Points Fighting with Kiai Jitsu – Sound Emission and Projection Fighting.