Third and “Final Season” of the Monogatari Series, part 3/5. Contains the arcs Ougi Formula, Sodachi Riddle, Sodachi Lost and Shinobu Mail from the Owarimonogatari light novels.
 
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 Suruga Kanbaru. Ougi tells Koyomi that she has something she wishes to consult with him. When she draws the map of Naoetsu High School, she finds something peculiar on there. 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.
 
(Source: Aniplex)
 
Note: The first episode aired with a runtime of ~48 minutes as opposed to the standard 24 minute long episode.