Owarimonogatari is back, and promises to inch ever closer to the endgame of the sprawling story of Araragi Koyomi and the town “where a white snake once reigned.”
At some point after the “hell” he went through over spring break, Araragi Koyomi visits Gaen Izuko at the North Shirahebi Shrine…and she murders him. He wakes up to find none other than Hachikuji Mayoi (her usual age) there to greet him.
After his customary hug (this one being one of the more elaborate and extreme ones) and a lot of inappropriate contact, Mayoi punishes him with her signature pit bull-like chomp. She informs him of what’s going on: he’s dead and currently in real hell (specifically in Avici, the lowest form of hell, due to his vampirism).
Mayoi is in hell because both her parents outlived her, and so spends eternity stacking up stones by the riverbank. Especially for a little kid, she’s remarkably calm and fine with this, with a “that’s the way things go” attitude.
They then commence an epic, trippy ascent up through the layers of hell so that Koyomi can meet someone. He’s shown all of the moments that preceded his making key decisions in his life, from finding Shinobu to catching Senjougahara to everything else; and the recurring reaction is that if given an opportunity to return to those moments, he wouldn’t change a thing.
His only exception is the incident with Nadeko, but Mayoi assures him he’s being overly tough on himself for not being omnipotent, which no one is.
The long, reminicing journey finally brings him to another iteration of the Shirahebi shrine, where Tadatsuru Teori is waiting for him. It turns out Gaen Izuko’s murder was far from random, but part of a larger plan to exorcise Koyomi of his vampirism. Sending him to hell was merely a side effect.
Teori presents Koyomi with a white snake-like rope back to the world of the living where he belongs, and when he returns, he will no longer be a vampire, which if you as me is huge.
Koyomi worries if he’s really the most worthy person to be resurrected, and Mayoi, punches it into him that of course he is: he loves to be alive, and cherishes his girls and has done far too much for them to simply accept death and a life in hell.
Koyomi turns Mayoi’s own positive vibes onto her, grabbing her at the last minute to drag her back into the living world with him, which she doesn’t seem to have expected, but Izuko is nevertheless pleased he did. Izuko, by the way, is on the cusp of being killed by Shinobu until Koyomi returns; clearly the vampire wasn’t pleased about the stunt the specialist pulled on her master.
Teori also informed Koyomi of the person who requested he exterminate him: Oshino Ougi. Izuko leaves Koyomi, Shinobu and the resurrected Mayoi alone, looking forward to the “battles to come” where she hopes to enjoy a slight advantage.
In the meantime, after a mad, psychedelic metaphysical odyssey through the underworld, Koyomi heads off next for something as mundane as his college entrance exams.