Natsume's Book of Friends, Vol. 29 (manga)

When Natsume and his friend Tanuma help a young woman find her way through the woods, they end up having to take cover from a storm in a mysterious mansion! The shelter comes at a cost though, and the boys are cajoled into joining a séance to summon a yokai. But when a sudden power outage disrupts the ritual, Natsume, Tanuma, and Nyanko Sensei are faced with something far more strange than the errant yokai they were expecting!