By night, teenager Yoshimori Sumimura is a "kekkaishi"—a demon-hunter who specializes in creating magical barriers around his prey. By day, Yoshimori's got other demons to battle: an addiction to sweets and a seriously crotchety grandfather! Yoshimori's pretty neighbor and childhood friend, Tokine Yukimura, is also a kekkaishi, but their families are feuding over who is the true practitioner of the art. With the help of their new kekkaishi-in-arms Gen, Yoshimori and Tokine battle the Dark Watchtower, a mysterious cabal of hideous ayakashi demons, to defend Yoshimori's ancestral lands! But the three friends are badly outnumbered, and when Gen's fury causes him to go too far, they may lose him forever—in more ways than one...