Tenketsu (天穴, Heavenly hole) is a basic element of the Hazama-Ryu Kekkaijutsu (though the term is also used to describe the Shakujō itself, named for the technique it is utilized in), used to prevent Ayakashi regeneration by sending their remnants to another world. Even after collapsing a Kekkai around some Ayakashi, noticeable fragments of their bodies may remain. In order to stop them from possibly regenerating from these remains, a Kekkaishi uses the hole in their Shakujō to vacuum up the fragments, sending the pieces to another world. The larger an Ayakashi is, the more likely it will leave remnants behind. In the cases of Ayakashi that ignite or are destroyed in explosions, Tenketsu can even collect fragments that are still ablaze.
Tenketsu is later revealed to have an alternate use: using a special, pentagon-shaped Shakujō with a triple leaf design at each corner, the hole can also function as a means to connect nontraditional Kekkaishi to the hidden spirit world of a Shinyuuchi, allowing them to make contact with the land's master.