The series is about Sumimura Yoshimori and Yukimura Tokine, heirs to two rival clans of the art nuclear kekkai (magic barrier), they must defend their school of Ayakashi (demons) who are seeking the mysterious powers hidden under the school field as it is built on one of the shinyuuchi which are considered sacred ground.
Long ago, demons attacked, the Ayakashi, a prince in order to steal his magical powers and rule the world. But the monk Tokimori Hazama held the demons. When the prince died, he sealed his power in Karasumori. Both of his students watched it now, that the power Ayakashi not torn itself. They made use of their magic arts, "Kekkai" in the fight against the demons. The Kekkai are magical shields, with which the demons and ghosts captured and can be destroyed.
