It's the end of the world as we know it, and Araragi most certainly doesn't feel fine - a feeling not helped by the fact that he and Shinobu's attempt to communicate with any other potential survivors in this apocalyptic wasteland have instead attracted only a teeming swarm of zombies-cum-vampires.
Actually, that isn't strictly true, as a rice shower which sends the "zombies" scarpering for some reason brings with it a helpful survivor... not just any survivor either, but a fully grown Mayoi Hachikuji. Although she doesn't recognise the boy that saved her in her youth beyond a vague sensation that they've met before, Hachikuji does have a letter for him and Shinobu - a letter penned by Oshino, no less. To keep it simple, this letter explains that what they see before them isn't the fact of their world but rather an alternate version of it, and implores Araragi to save this world (or at least what remains of it) by facing off against the source of its malaise, Kiss-shot Acerola-orion Heart-under-blade.
Without any real powers to speak of or much hope of winning in a straight-up fight against a wounded but still fully functional Kiss-shot, Koyomi and Shinobu nonetheless head off to face their opponent. Upon meeting Kiss-shot however, it becomes clear that conflict isn't the order of the day here - she bears no ill will towards Araragi, and indeed is happy to offer up the energy required to send him and Shinobu back to their own timeline. Thus, this world is saved by virtue of placating Kiss-shot, while Araragi gets to return to his enjoyable life in his own world, replete with Hachikuji and all.
Although it exhibits a lot of the same sense of story-telling that has been a trademark of all things Monogatari from the get-go, this Kabukimonogatari story arc simply... well, wasn't that interesting. For a story focused around Hachikuji she played very little part, the climax to the tale was decidedly anti-climatic, and the apocalyptic setting prevented the series from doing what it does best in terms of dialogue and witty repartee. That said, there were still some nice character moments and smart little twists here and there, but as a whole this certainly isn't Monogatari at its most powerful, and as a result it feels like rather a come-down after the superb opening story arc of this series.