By night, junior high student Yoshimori Sumimura is a "kekkaishi" - a demon-hunter who specializes in creating magical barriers around his prey. By day, Yoshimori's got some other demons to battle: an addiction to sweets and a seriously crotchety grandfather! Yoshimori's pretty 16-year-old neighbour and childhood friend, Tokine Yukimura, is also a kekkaishi, but their families are feuding over who is the true practitioner of the art.

Karasumori, the magical area that Yoshimori and Tokine have been assigned to protect, is a place of mystery and wonder. Beneath its surface lurks Lord Uro, a fantastic doughnut-loving creature who only appears when he needs a helping hand with home repairs. Yoshimori has been assigned the task of handyman. The only problem is that Uro's home lies in the depths below Karasumori, where the magic is strong enough to have ill effects on humans.