Kekkaishi, Vol. 18 (Kekkaishi #18)

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.

Brother must rely upon brother in a daring escape! So why does Masamori send Yoshimori's friends to spy on him at the Karasumori Site? Then, when a flock of beautiful butterflies descends on Karasumori High School, all the students are in peril... How can Yoshimori single-handedly battle thousands of tiny ayakashi without harming the people in their midst?