Natsume Yuujinchou: Season 3, Episode 7

3 - 7: Exorcist

Natsume finds out who's been stealing the youkai blood: the exorcist Matoba Seiji. He investigates with the help of Natori, but is captured by Matoba's servant youkai. Matoba is willing to sacrifice any number of youkai for his own ambitions. He tells Natsume why he's gathering blood: to release the seal on a powerful youkai. Natsume learns that there are people who treat Youkai in a totally different way than he or even Natori.