Koyomi Araragi begins the day by being rudely awoken by his sister, Tsukihi. He decides to discuss love with her, asking how one can tell if they are in love or not. It turns out that recently, he can't stop thinking about his classmate, Hanekawa Tsubasa. Later, he runs into Hanekawa, who reveals a shocking fact which he may not tell anyone else about.

Araragi, initially ignoring Oshino's warning not to involve himself any further in this incident, visits Hanekawa's house and is shocked by what he finds. He returns home and convinces his sisters not to involve themselves in the Curse Cat incident either. A few days pass and Hanekawa is still nowhere to be found. Araragi returns to Oshino to find him severely injured from his numerous encounters with the Curse Cat. Later, Araragi manges to find and talk to the Curse Cat occupying Hanekawa. Calmer and less violent now, she tells him to leave her to her own devices in order to relieve her master's stress.

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.

After the graduation of Araragi and Senjougahara, Suruga alone to deal with her left hand that has been turned monsterous from her mother's monkey paw charm. After hearing rumors of a "Devil" that can solve one's problems no matter what, Suruga set out to find this person.

Rouka challenges Suruga to a one-on-one basketball match as the two discuss the events that led up to their collection of their respective "devil" parts. Suruga is still coming to terms with the ability to use her left arm again.

Koyomi Araragi and Shinobu Oshino discuss the true nature of Shikigami doll Yotsugi Ononoki, and Koyomi is being rudely woken up by his sisters who tell him to cram for his upcoming college entrance exams.

Koyomi Araragi sees that he has no reflection, and discusses this with Shinobu. She then suggests that Koyomi should see Yozuru Kagenui and Yotsugi Ononoki.

Koyomi and Yotsugi land at the base of the mountain, where they are surprisingly met by Ougi Oshino. She talks with Koyomi for a while about his current situation and his upcoming confrontation with Teori. Koyomi and Yotsugi begin their journey up the mountain.

Karen asked Koyomi for advice regarding a mysterious grown tree that suddenly appeared on her dojo's backyard.

On his way home, Araragi sees Yotsugi, who asks him for help finding something.

When Koyomi asks Yozuru Kagenui about the extent of her relationship with Yotsugi, she challenges him to a fight. But then Yozuru disappears...

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.

After being exposed, Ougi is about to be engulfed by the darkness, but Koyomi refuses to give up on her and Meme reappears in the nick of time to save them.

Koyomi Araragi contemplates the current state of his life post-graduation when he suddenly gets pulled through the mirror into a mysterious yet familiar world...

Koyomi attempts to make sense of the mirror world with this world's counterparts of his acquaintances. Later at night, Yotsugi then takes Koyomi to meet yet another person from this world.