This one does something no real anime can: it hands Kawakami sickos the thing they've begged for, then yanks it back before the credits. Owari no Chronicle is the sprawling prequel spine that Kyoukai Senjou no Horizon keeps gesturing at, the series everyone assumed was too dense, too concept-heavy, too much Kawakami to ever get animated. So when an adaptation announcement dropped on April 1, 2012, half the fandom lost its mind before the other half checked the calendar. That gap, the few seconds of genuine belief before the gut drop, is the entire artifact. It is one episode, it is a prank, and it is still the closest thing to an Owari no Chronicle anime that exists. If you've ever explained the Concepts to someone at a con and watched their eyes glaze, this is your monument to a hope that never got made.
Owari no Chronicle is a single-episode special from 2012, put out as an April Fools' prank rather than a real series. It presents a supposed anime version of Owari no Chronicle, the light novels that act as a prequel to Kyoukai Senjou no Horizon. The special carries action, adventure, fantasy and sci-fi genre labels.