Natsume's Book of Friends

Natsume accidentally bumps into a woman with blood covering her body. He follows the bloody footsteps that the woman left and discovers a small house. When he opens the door, he sees badly injured youkai. There is someone killing youkai for blood, and with the help of Natori, Natsume tracks down who he believes to be the murderer: Matoba. However, Matoba captures him.