NisiOisisn is an enigma. After Tsukimonogatari being a long-winded swamp I just made myself wade through in order to progress further in the story and Koyomimonogatari - after me being all hyped for it after me seeing an awesome trailer for the miniseries - being so boring that for once I didn't find myself looking forward to reading in the evenings, "Owarimonogatari" is the most fun I've had with the Monogatari series in a long while. This is without a doubt my favourite entry to the "Final Season" of Monogatari so far, and in the ranking of my favourite novels in the series in total, it would be among the first few ranks.
This has mainly to do with a lot of factors, but the deciding one that made this novel stand out from the rest of the series was without a doubt the utterly comical and shockingly fascinating implementation of math and the detective mystery genre into a very entertaining Monogatari novel. These three parts seem like something totally disagreeable on paper, but the fact that Isin not only was able to craft a compelling tale involving math in the manner of a series of mystery short stories but also made these themes connect and relate to each other in a logical way that never once made me question their legitimacy in the series is a proof to just how good of an author Isin truly is.
This is partially due to the brilliant character of Oikura. Having had no previous mention in the series whatsoever before, Isin implements her into the story in a so organic and natural way that I never could imagine the Monogatari series without her. She as a character is constantly evolving over the course of the novel; not because she is actually changing but because we find out more and more about a character totally unknown to us beforehand.
More than in previous volumes, Isin actually has several layers of social commentary in this one. I don't want to spoil anything, but I got the impression that he wanted to comment on almost every hazard that could befall a teenager growing up in Japan, in the school as well as domestic space.
As always, the characters and their interactions are superb. But this entry is actually pretty hype, because Ogi finally kicks into action! We still don't know what exactly they (I am still confused about their gender to be honest … I can't fathom whether Ogi referring to themselves in "Hanamonogatari" was just Ogi/Isin toying with the reader or some Canon gender commentary) are up to and what is actually up with them, but the sides in a battle (of either wits or force) that seems almost unable to prevent by now are getting clearer and clearer. Ogi in one of the first characters in a book that I am genuinely creeped out by, and I enjoy every page featuring them.