Owarimonogatari

Ougi Oshino arrives at Naoetsu High and points Koyomi Araragi toward something impossible in the building's layout: a classroom occupying space that should not physically exist. When the two investigate, they find themselves trapped inside a mystery tied to an incident from Araragi's past that he has tried to forget.

Finding a way out becomes an encounter with his own memory and eventually leads to larger questions about Ougi herself and the events that shaped his ideas of justice and guilt. As buried details surface, Araragi must reconsider stories he has been telling himself for years. Some supernatural mysteries can be solved through observation and logic, but the hardest one is often the version of the past a person constructs to avoid a truth he is not ready to face.