Despite this show's title, last week's penultimate episode brought rather a shock as to the true nature of the "fake" in question, with Tsukihi's place in her own story arc becoming entirely clear.
As per the "Karen Bee" story, we quickly learn that the true nature of Tsukihi's supernatural being doesn't actually relate to that of a phoenix - in fact, she's more like a cuckoo with regards to her place in the Araragi family. Such arguable trivialities aside, it's up to Koyomi to decide how to react to this surprising news - will he continue to defend Tsukihi no matter, or is this a rare opportunity for the eldest Araragi sibling to take a step back and admit defeat.
There are, of course, no prizes for guessing which course of action Koyomi takes, and after ensuring that Shinobu is sufficiently "powered up" by his blood both herself and Koyomi set out to challenge Yodzuru and Yotsugi to a good, old-fashioned brawl to sort things out. While Shinobu's true power is clearly rather fearsome even in her current state, Koyomi has little to offer but sheer tenacity - but then again, is he even trying to win his particular battle? Ultimately, Koyomi is there to trade opinions rather than blows, as he tries to convince his opponent Yodzuru to leave Tsukihi alone and safeguard his family as the series rolls to a close.
As a finale goes, this closing episode of Nisemonogatari offers everything that you might expect - lots of dialogue, and our protagonist ultimately trying to talk rather than fight his way out of a predicament to the point where he's happy to be beaten to a pulp to take the non-violent route. A little too much censorship/corner-cutting aside, it makes for a reasonably satisfying ending, even if little time was given to really building up and resolving the Tsukihi Phoenix arc, but what of the series as a whole? It's certainly a very different series compared to Bakemonogatari, which is a disappointment in itself; its presentation and constant attempts at titillation often making it feel more like slickly written fan fiction than an actual story given the way it handles its characters and scenarios. While these side-stories and the show's gorgeous, symbolic visuals can work towards adding quite a lot to the show, its wider descent into smut and sexual content doesn't really do it any favours compared to its mostly quietly sexy predecessor. Overall, the only word I can really find to describe Nisemonogatari is "interesting" - there's a lot to explore and consider within it and its framework, but such complexities tend only to try and hide the fact that they're propping up some decidedly weak and not particularly interesting stories. Taken from that standpoint, Nisemonogatari is a huge disappointment for me given that it's the one show I'd been waiting with bated breath for this winter anime season.