Ki is a natural power that exists in all living things, there are also a number of Ki-Based Fighters (氣功格闘士, Kikō Kakutō-shi).
Differing from magic which exists in higher beings such as Gods, Demons and Spirits, Ki exists in abundance on Earth, as well as within living beings like humans and animals and it also exists in the Five Elements. There were also rare Ki-Based Fighters able to use their ki in combat, although their numbers are few due to relying mostly on the power of the Four Gods.
Ki-Based Users are able to release ki waves from them making it effective for either almost all forms of combat. A well-trained user is also able to absorb the ki found in the Five Elements, letting a practitioner cover themself in a specific colored aura: Fire (Red), Metal (white), Wood (blue), Earth (Yellow), and Water (Black).
Shiba who is a Master Ki-Based Fighter is able to overload the ki of others such as Takashi Hayase despite him blocking his strike and putting him in a near-dead state, leaving a skilled healer such as Kaoru Nonaka with little to no options to heal him even using her healing magic. If it wasn't for Basara using his Banishing Shift to get rid of the ki, then it would have resulted in Takashi's death. He is able to also control the ki found in powers such as Basara's Banyuusekiryoku and Shoumetsukensen. Although Ki is dependent on the spirit of the user, Shiba is able to produce infinite ki due to having the soul of Reginleif.
However, how ki is used is based on the spirit of the user, meaning that most were limited to their own ki.
Ki Sense: Ki-Based Users are able to sense things such as killing intent and presence things, which are related to ki letting him predict the attacks of others. Shiba can sense the ki from children even in their mothers' womb despite being in mere days of developing.
Ki Barrier: This is the ultimate defensive technique, where the user envelops themself in ki, letting them nullify attacks that would be fatal.
- In Volume II, it was first hinted as Shiba could sense what was happening in the dimensional barrier where Basara and the others were fighting.