Zoku Owarimonogatari (Movie)

With the battle with Ougi Oshino over, it was finally time to graduate from Naoetsu High School the next morning. Araragi Koyomi, after waking up, goes to wash up in his bathroom, but when he leaves, he notices his reflection staring at him, not moving. He touches the mirror and is pulled into another world where he notices everyone that he knew has manifested as their inner selves and ambitions. Araragi, in order to not influence the world, has to find a way out of this mirror world, but he begins to realizes that there's more to it than meets the eye. It is "the continuation of a dream you forgot about yesterday." (Source: MyAnimeList)