Natsume Reiko's grandson Natsume Takashi received the "Book of Friends" made of those contracts from his grandmother's relics. He can also see objects that do not appear in front of others. And like Reiko, she became alienated by the people around her and was called a "liar" by her peers. However, as the only one who inherited Reiko's bloodline, he made an important decision: to return the names of the monsters that Reiko had taken away one by one. Around such Natsume, various monsters began to gather... Natsume Takashi, a boy who could see monsters, and a monster cat teacher who looked like a lucky cat, began a journey to return their names to the monsters, and encountered many heart-touching stories...