Nadeko becomes the focus of Monogatari once again as a new story arc begins - despite reeling off a glut of information about her this isn't the Nadeko we know and love however, but a Nadeko Medusa (for that is the story arc's name) with snakes for hair and an overwhelming desire to kill Araragi; something it seems that she's more than capable of doing judging by the opening scenes of this episode.
Rewinding back to the start of all this, we find Nadeko preparing herself for a normal day at school, and by normal I mean "depressing" - it seems that the trickster Kaiki's influence (see Nisemonogatari for more details) has cast a pall over her class in particular, fostering a sense of isolation and mistrust between the students within the class which leaves it a miserable place to be. On her way to school, Nadeko bumps into (or rather, is avoided so that no bumping occurs) Ougi, who introduces herself and waxes lyrical over whether Nadeko's previous encounter with an apparition has her pegged as a victim or not.
If going to school was already on Nadeko's list of things she isn't looking forward to, this isn't exactly helped by her seeing white snakes cropping up all over the place - figment of her imagination or not something isn't right here, and after calling Araragi to ask for his assistance she agrees to meet him that evening. That might just be too late however, as Nadeko is approached by Kuchinawa, a snake of some kind of who seems to be looking for some kind of penance from Nadeko for the snakes she killed while trying to waive the effects of that aforementioned apparition. It seems that there's little choice for our protagonist for this story arc but to accept the fact that she'll have to do Kuchinawa's bidding; little does she know exactly what this "favour" will entail.
I'm not a big fan of the whole "show the ending (or something close to it) first" narrative conceit when it comes to a show like this - I'd rather just see how things pan out without that prior information - but that aside this feels like an interesting use of Nadeko's personality and character, coupled with her back story from the previous series, that seems to be pretty promising at this juncture. We shall have to wait and see what it has up its sleeve for now though. Snakes, I imagine.