Koyomi returned from the time warp with Shinobu. From North Shirahebi Shrine, he headed home together with Mayoi Hachikuji and returned her backpack to her. However, right afterwards, the two of them are assaulted by a mysterious “Darkness.”

With the help of Yotsugi Ononoki, Koyomi and Mayoi were able to escape from the “darkness.” Within the ruins of the cram school that they escaped to, Shinobu is consulted about the “darkness.” She starts to speak of what happened 400 years ago.

Koyomi finishes hearing the story about 400 years ago from Shinobu. Yotsugi joins them at the spot, and Mayoi wakes up from her slumber. The four of them were talking within the cram school ruins, but the “darkness” appears a second time at that location.

Koyomi and company climbed down the mountain they were hiding in after escaping from the “darkness." Upon visiting a village between the mountains, they meet Izuko Gaen and receive an explanation concerning the “darkness.”