Owarimonogatari follows the events of Koyomi Araragi as he meets a transfer student that turns his world upside-down.
During the month of October of his third year in high school, Koyomi Araragi is introduced to a transfer student named Ougi Oshino by his underclassman Kanbaru Suruga.
Ougi tells Koyomi that she has something she wishes to consult with him. When she draws the map of Naoestu High School, she finds something peculiar on the map of Naoetsu High School she draws. This discovery reveals a tale that wasn’t meant to be told, and this makes Koyomi’s high school life totally different.
This is the story that brings to light “what” makes Koyomi Araragi. This is the story that reveals the “beginning” of everything.