Madara, commonly known as Nyanko-sensei, is a powerful and ancient youkai who takes the form of a round, lucky-cat-like creature. Initially, he appears to be after the Book of Friends owned by Takashi Natsume, but over time, he becomes Natsume's loyal protector and close companion. Despite his gruff and sometimes greedy demeanor, Madara genuinely cares for Natsume and often helps him interact with both humans and spirits, playing a key role in the series.