The series revolves around a 14 year old boy named Yoshimori Sumimura the legitimate heir as kekkaishi in his family. For hundreds of years his family has served as kekkaishi, or in simpler terms exterminators of ayakashi (monsters). However the Sumimuras aren't the only kekkaishi, their rivals and next door neighbors, the Yukimura's are also descendants of kekkaishi. The Yukimura's legitimate heir is 16 year old Tokine Yukimora. Yoshimori and Tokine have known each other since they were children, although their relationship is rather complex they view each other more as friends opposed to rival kekkaishi. Yoshimori and Tokine, with the aid of their ayakashi hunting ghost dogs Madarao and Huckibee, must defend Karasumori, a sacred ground that attracts and strengthens ayakashi. In order to protect the people he loves from harm Yoshimori must become stronger, and train his body and mind to control his given powers.