An inexperienced exorcist tries and fails to completely seal a youkai near Natsume's school.  Natsume decides to take the pot the youkai is sealed in to Natori, in hopes that it can be disposed of properly. While he's there, he learns that there is an ongoing feud between exorcists lately, and that one exorcist in particular is attacking his rivals.  When Natsume gets home, he finds that Matoba, another exorcist who's tried to take advantage of him in the past, wants his help dealing with just that particular problem...
But that's what youkai are.
Pero así son los youkai, ¿no?
Mas é isso que são os youkais.