This is Ougi Oshino. And while she’ll be a major character in later arcs, she’s just here to say hi!
Anyways, this is Otorimonogatari, containing “Nadeko Medusa”. That’s right, it’s all about Nadeko Sengoku, and you’ll love Kana Hanazawa’s character doing cute things and whatnot!
Now if you remember it correctly, she’s was a victim of a serpent curse during Nadeko Snake from Bakemonogatari.
On this arc, she’s attracted again by a snake. Not an ordinary snake…
…but a god whose body was lost and his home was destroyed (or so I thought). While the serpent god becomes Nadeko’s partner, things got worse from there.
It turns out, she’s just pretending to be a victim and decided to become a yandere by swallowing Izuko Gaen’s talisman being kept by Koyomi-oniichan, stabbed him and Shinobu-chan to death (but still breathing), and proceeded to kill the rest of Koyomi-oniichan’s harem 6 months later. The end!
First of all, why would NisiOisiN end Otorimonogatari where everyone dies while Nadeko laughs maniacally? Sure, she’s revealed to be a lunatic all along, beginning at Part 3 (which is Ep. 14) where she becomes a loudmouthed jerkass, but the fact that Nadeko killed Koyomi-oniichan out of one-sided love (plus his harem) is so contradicting in my opinion that this series would end abruptly.
So you’re thinking “Oh c’mon, it might be a dream or a Nadeko’s imagination!” Whether if it’s a dream or not, this ending is so fucked up that I might barf how terrible is. And poor Araragi-kun, his body is so broken that he can’t re-attach it with his own vampiric powers.
The only I like on this arc was the fact that Kana Hanazawa can do any voice from being a loudmouthed bitchrep to a homicidal yandere. Of course, her performance alone won’t save this arc.
Now that the arc is over, I guess SHAFT would do now is to “revive” Araragi-kun and his harem, forget everything that happened on this arc, and move to the next one (after the recap).
The end is just how Nadeko thought things would turn out in 6 months, the moratorium set by Hitagi. It’s a preview of things to come. Next arc is quit a bit of flashback with Onimonogatari (Shinobu Times) and the story with Nadeko gets wrapped up with Koimonogatari (Hitagi End).
Someone told me that it’s all in Nadeko’s head, but still I don’t think this arc would end this way.