While taking Karen to meet Kanbaru, Araragi is put into a compromising position. On the way, he runs into someone asking about familiar things.

Koyomi and Shinobu unexpectedly time warped back to May 13th 11 years ago. Koyomi thinks of saving Mayoi Hachikuji, who was “destined to become a ghost after getting into a traffic accident on her way to see her mother the next day – Mother's Day."

A recap episode retalling the events of Bakemonogatari's Tsubasa Cat and the entirety of Nisemonogatari, narrated by Koyomi. During the summer vacation after all the apparition-related incidents around the five girls have been resolved, Koyomi Araragi's two risky younger sisters – the self-proclaimed heroes of justice, Karen and Tsukihi – become involved in some trouble.

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.

Kaiki heads to North Shirahebi Shrine daily in order to deceive Nadeko the snake god but finds himself being followed on his way home. Furthermore, he gets a mysterious threat telling him to “pull out of this case.”

Mayoi takes Koyomi to meet Teori, who offers him a way to return to the world of the living. Koyomi is in doubt about accepting his offer, as he believes others like Mayoi are more worthy of reviving than him, until he comes with a surprising decision.

Gaen assembles Koyomi, Shinobu, Mayoi and Yozuru and reveals that Ougi is the responsible for some of the previous ordeals they faced.

To stop Ougi from meddling further, Koyomi has a final confrontation with her.