Owarimonogatari, Part 3 - NISIOISIN

From the best selling novel series comes the latest book of the final season of the MONOGATARI Series. During his third year in high school, Koyomi Araragi is introduced to a transfer student named Ougi Oshino. Ougi tells Koyomi that there is something odd about Naoestu High School... a secret room on that''s not on the map. What will Koyomi and Ougi find in this hidden room?