Natsume Yuujinchou S02E01 - The Stolen Book of Friends

While outside during school Natsume is hit with a ball while reading. He goes to retrieve the ball and ends up breaking a Youkai's seal (much like he had with Nyanko-sensei). Later that night Natsume and Nyanko-sensei discover a look-a-like of Nyanko, only to have him steal the Book Of Friends!