Tamashii Reiki is based on the Conscious Awareness of natural energies and their pathways. Energy leaves it's source, travels it's destined pathway, and eventually returns to the source.
This is true on Every level of Existence. The Chinese call it the cycle of Creation and Destruction. It is most evident among the physical elements. A tree grows, sheltering, shading and providing oxygen those near it. Lightning strikes the tree. The tree burns, releasing excess carbon dioxide into the air while taking oxygen away. The embers of the tree become ashes that nourish the ground. This allows for new growth which will take in the carbon dioxide that was created and release oxygen. This process is no different on the Etheric level. Things that we say or do have their effects on the people and things around us. The energy behind those effects then returns to the source. This is generally called Karma. It is the one Law of Existence. The purpose of this Law is to maintain Balance throughout Existence.
Most religions would have you believe that we are separate from the Divine Source. That is impossible, because we are formed from the Source. In theory, we serve our purpose and then return to the Source. There was never a separation, except in our Minds. This perceived separation resulted in the severe blockage of the energy needed to sustain life and evolve Spiritually. The purpose of Zen Reiki is to unblock the channels that Divine Energy uses to fuel our existence. This process allows for easier communication between one's conscious self and one's Higher Self.
So how does that work? Ideally, Divine Energy flows into the body from the Crown (top of the head) and the Root (feet) simultaneously. The Higher vibrational Energy enters through the Crown and flows down the center/right front of the body. When it reaches the Solar Plexus (about an inch above the navel) it travels to the center/right/back of the body and out through the feet. Grounding Earth energy rises up through the feet. This Lower vibrational Energy travels up the center/left/back of the body. When it reaches the Solar Plexus it travels to the center/left/front of the body out through the Crown. This pathway requires conscious effort to maintain.
Lower level energies, those that govern our physical bodies, are very intense and dense. They generally don't want to move much higher than the Solar Plexus. As a result, humanities primary concerns are our “stability” (root chakra), “sexual practices” (sacral chakra), and our “Ego” (solar plexus). The Higher Energies tend to want to say around the Throat. Study of the Divine (Crown), intellect and/or psychic prowess (3rd eye), and teaching and/or expressing one's self are the concerns of those that are more in tuned with their Higher energies.
The Heart Chakra is the transmutation point. It is the Point that the Lower Vibrations are raised to rejoin the Source and Higher Vibrations are lowered to be Grounded into the Earth. Another way to put that is: Divine Will is manifested on the physical plane (grounded) through Lower vibrations being raised to serve Divine Will.
Tamashii Reiki is not a Spiritual Path or religion, in and of itself. It is more of a vehicle, like Meditation.
To totally paraphrase The Buddha, “When you get to your destination, get out of the car.”
Tamashii Reiki is the car, or rather bulldozer. It is used to cleanse the Pathways and cross points (chakras) so that Divine Energy can flow unimpeded. Once the Pathways are cleared, it's up to the Seeker to maintain that connection. The Path doesn't matter, as long as the Seeker can hear and act in concert with their Higher Self.