You know how to tell the difference between an adult and a child, right? Children have only see the Nausicaa movie. Adults have read the manga.
As if two volumes of Bakemonogatari and the Kizumonogatari prequel weren't enough proof, Nisioisin is always at his best when he's allowed to write whatever the hell he wants to. This volume is, in theory, focused on the elder of Araragi's two Fire Sisters, Karen, who always wears her school track suit, has become an exceptionally accomplished martial artist, and to Araragi's horror, is now taller than him. Hot headed, she is always ready to fight for someone in need...much like Araragi, although he refuses to admit it. She acts before she thinks, and this eventually gets her in trouble with the apparition of the week, a bee with a sting that infects with a terrible fever.
I say eventually because this happens fully halfway through the book. It opens with Araragi handcuffed to a post, and then proceeds to backtrack through the day as he attempts to figure out which of the many, many reasons Senjogahara would have decided such drastic measures were appropriate. All members of his harem get their chance to boldly cross lines he never quite crossed before.
One big question here involves the departure of Oshino Meme. It looks like his role is going to be filled by Shinobu. Despite not saying a word throughout Bakemonogatari, she abruptly begins speaking again here, her personality completely unchanged from Kizumonogatari. This is cheerily explained as her being bored, and Araragi consistently failing to buy enough Golden Chocolate at Mister Donuts.
There is an actual plot of some kind, which feels like an afterthought. The actual resolution to this plot comes in a brief conversation that essentially serves as an extended epilogue - the real climax to the book comes in the thirty page long fight scene between Karen and Araragi, as he tries to convince her to let him handle things. Fight scenes were initially one of the Nisioisin's biggest weaknesses; his ornate, roundabout style doesn't really lend itself to the direct precision required to effectively communicate action, and the pacing often shuddered to a half. If nothing else came out of Katanagatari, it seems to have at least helped him work through this issue; the fight in Nisemonogatari is long as hell, and involves quite a lot of seriously complicated descriptions of capoeira style bodies twisting through the air that I honestly couldn't be arsed to completely follow, but he managed to keep the tension going even with only a hazy grasp of the action, and for the first time, really managed to apply the structural confidence of his conversations to his action. It winds up being pretty powerful stuff.
Looking forward to the second volume.