While on a quest to find Nyanko-sensei, Takashi Natsume encounters Mitsumi, a timid youkai tasked with waking the powerful ayakashi Gantetsu from his slumber as the 'Ishi Okoshi' for the year. Moved by Mitsumi's dedication, Natsume decides to aid him in this mission, but they face a race against time as others seek to awaken the divine being as well. In another event, Natsume's friend Kaname Tanuma is approached by a mysterious man who turns out to be a youkai in disguise. Despite the youkai's assurances of harmlessness, Tanuma's health starts to decline, leading Natsume to question the visitor's true intentions and his ties to Tanuma.