Karuna is a Sanskrit word and is used in Hinduism, Buddhism, and Zen which means Compassion. Karuna could be translated as "Compassionate Action." – Any action that is taken to diminish the suffering of others. When one attuned to Usui Reiki, he constantly works with higher frequencies, as Reiki easily connects you to your Higher Self and other Higher realms.
As a result, your chakras get aligned with these frequencies, and can easily connect you to other realms.
Karuna Ki is more subtle, and the Karuna Ki symbols carry the energies to connect you more easily to higher realms.
Zonar symbol is used to heal painful memories, trauma, and emotional scars in both the past and present. Zonar is considered to be one of the most powerful Karuna symbols because it penetrates deep into the mind and body to get rid of negative energy. It stretches all the way to the very root of the problem and provides support for deep, emotional healing.
Shanti is the symbol of peace, calm, and tranquility. It is the last symbol to be learnt in the Karuna Reiki healing process. Shanthi is considered to be the most powerful Reiki symbol with its high level of vibration. It is used in Reiki healing to open up emotional traumas and heal them with peaceful thoughts.
Halu is a Karuna KI symbol that is used in combination with Zonar to strengthen the Karuna healing process. Halu is used as a safeguard for preventing harmful energy from entering the mind and body. This symbol has a pyramidical structure which provides all round protection from psychic and emotional manipulation and reacts to even the smallest strands of negative energy by forming a protective shield around the healer or receiver.