Keirakukei (energy pathway system) is the term for the theorized channels within the body that transfer and channel ki. The body has many systems designed to do various tasks. The circulatory system moves blood, the nervous system carries the body’s nervous impulses to the muscles and sensory impulses back to the brain. Simply put the keirakukei serve the same function for ki as blood vessels do for blood. These channels are a naturally a curing process in the body, however they are extremely thin allowing a minimal amount of ki to pass through. Martial artist train in expanding the size of these channels, allowing their ki to flow more swiftly and in greater access. However no matter how skilled an individual is or how wide their channels are their body will be protected by a series of naturally accruing flood gates. These gates limit the overall flow of ki within a person's body. The basis for the idea of the flood gates comes from the body's limits on the functions within it. This makes the body much weaker, but it keeps the body from expiring too soon.
Burning soul opens the natural flood gates of the body allowing for an immense burst of ki within the user vastly sharpening every aspect of the body. Since the floodgates are open excess energy radiates from the body in the form of a pulsing flame-like aura. The skin becomes slightly redder due to increased blood flow and the muscle mass is increased creating a slightly bulkier muscle structure.
This technique comes with a number of drawbacks however. Use of it causes a marked personality alteration, where the user becomes unusually aggressive and more prone to acting on impulse. The second drawback is that like fire the user’s battle aura will literally burn them from the inside out causing a catastrophic amount of pain, which is why training for this technique is considered nothing but torture. The user’s body has to become accustom to the pain in order to use burning soul effectively and that can only be done through repeated usage. The third and final drawback, and also the main reason the technique was forbidden. The burning soul places a great deal of stress on the keirakukei. Prolonged use of which extensive damage to it causing it to leak. The keirakukei would begin releasing small amounts of ki uncontrolled into the body which reacts by shaking. Continued stress can cause a complete system breakdown in other words death.