Natsume Yuujinchou Shi EP6 - Other Side of the Glass

Natsume is trapped in a bottle by a youkai to be offered to another named Omibashira. Nyanko-sensei transforms into Natsume and goes around his school to ask his friends about Omibashira, but gets Tanuma involved. Tanuma is attacked by one of the youkai that trapped Natsume and loses him, but as he runs through the forest looking for Natsume he finds a mansion behind the school. When Tanuma is suddenly able to see the youkai walking up the steps to the mansion, he is found out by a youkai with a bag over its head.