Sumimura Yoshimori is a normal 14-year-old middle-school student, though he always falls asleep in class. This is however due to his night duties, in which he takes on the role of a Kekkaishi (Barrier Master). Together with Yukimura Tokine, his neighbor and childhood friend (sweetheart), he serves as a protector for the school which holds a few ancient secrets. These secrets are slowly being unraveled, which may play a role in Yoshimori's ultimate plans.
They are heirs of the Hazama clan, thay became the kekkaishi protecting the land and the power. They use a technique called Kekkai, a form of magical barrier, used to capture and destroy Ayakashi (monsters/demons) that are drawn to this land. Any demons that come near the power will become stronger and therefore Yoshimori and Tokine are to guard the land from intrusion of the Ayakashi. Although some of the demons form a powerful organization to take over that mysterious power. Yoshimori plans to destroy not only the demons, but also to gain the power to completely save the world from being controlled by demons. To do that, he first needs to know what the power actually is, and also strengthen his poor kekkai skills.