Name: Takashi Natsume Age: 17-18 years old. Second-year high school student. Appearance: Cream-colored hair. Attends a school where he wears a gakuran uniform. Has the same eye color as Reiko. Personality: Good-natured. Because he can see yokai, he has a past of being treated as creepy during his childhood. He now spends his days with his partner-like companion, Nyanko-sensei. He inherited the "Book of Friends"—a bundle of papers containing the names of yokai collected by his grandmother, Reiko Natsume—and spends his days returning those names to the yokai. Reiko gave birth to Natsume's mother at a young age without marrying. She is Natsume's maternal grandmother.

Name: Reiko Natsume Age: 17-18 years old. Second-year high school student. Appearance: Long cream-colored hair, wearing a sailor uniform with a long skirt. Has the same eye color as Natsume. Personality: An elusive and mysterious person. It is said she could see yokai and possessed immense spiritual power. Because she didn't associate with humans, she played with yokai instead. She has met Nyanko-sensei before. She is widely known among the yokai. She is friends with Guest, as both are humans who can see spirits.

Name: Nyanko-sensei Age: Over 1000 years old. Appearance/Personality: A fat, round calico cat. His voice and preferences are like a middle-aged man's; he loves sweets, sake, and squid. However, his true form is a powerful great yokai named Madara. He is a partner-like figure to Natsume.