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 reexamines his options and is drawn to the bath in the Kanbaru household, but is suddenly attacked by the Rainy Devil. Koyomi narrowly escapes the danger, only to meet more people from this world he supposedly "knows".

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.

Koyomi meets the Shinobu of this world; as they converse, she reveals to him his powerful influence on the mirror world.

While taking a bath in the Kanbaru household, Koyomi has an encounter with an unknown yet familiar face who starts up a conversation about knowledge.

To put together the final pieces of the puzzle, Koyomi makes one final stop at his now-former high school to meet perhaps the most important piece of that puzzle.