Nyanko is a popular character from the Japanese manga and anime series Natsume's Book of Friends (Natsume Yūjin-chō). Nyanko is a round, chubby cat spirit who often takes on a cute, playful appearance. He serves as a protector for the main character, Takashi Natsume, and has the ability to transform into a more powerful form when needed. In the series, Nyanko represents themes of friendship and loyalty. His interactions with Natsume and other spirits highlight the importance of understanding and connecting with others. Nyanko's charm and humor have made him a beloved figure among fans of the series.