PietroParis

石川 Ishikawa is a very common signature on this kind of mass-produced souvenirs.

An obvious explanation would be that this is an imitation made in China or Hong Kong (and I would guess quite later than Taisho).

Indeed, it's a mass-produced souvenir: https://ebay.us/m/1HJRYB https://spicersauctioneers.com/catalogue/lot/3854b156aa2e7af44cf82585fc6f87b3/2a6fa85538c56e3991b429b74f737ad8/antique-and-fine-art-lot-294/ In these cases I usually suggest a comparison with a genuine example, but I don't recall ever seeing an antique version of this model. Anyway, this is what genuine birds in wood might look like: https://www.metmuseum.org/art/collection/search/59041

This is an old acquaintance, it was already there in 2021 (see page 2).

Namitoshi on eBay:

The "chick and egg" thing is indeed modern and mass-produced:

Another faux, sorry.

I'd say the signature is consistent with the whole piece: a modern fake.

I always thought that Schreger lines occur only in elephant and mammmoth ivory. A quck google search doesn’t provide any evidence of the contrary. https://cites.org/sites/default/files/eng/resources/pub/E-Ivory-guide.pdf

IMHO: The bird could be a carved tagua nut, in that case it might still have some age. The zodiac animals look modern (and possibly Chinese) to me, and I have doubts also concerning the bathhouse scene (those ladies look a bit too "buxom" for a Japanese antique, and also the faces don't look right). I have few illusions about the oni, but more pictures might help. P.S. concerning the others: the Dutchman is a modern fake, the shishi is not a Japanese netsuke (possibly Chinese soapstone of undetermined age), the bamboo shoot doesn't look very old but it's better carved than most in this bunch. The signature 孝正 Takamasa/Kosho is unrecorded, probably made up although it could also be some post-WW2 (or even contemporary) professional carver. P.P.S. as mentioned by others above, the smokers are a decent Meiji-period export piece.

On dating I would trust Ueda, who had access to documents such as temple registers, more than Meinertzhagen who relied on stylistic considerations. So I would take the 1907 death at face value. Either for some reason Kohosai stopped working for the last 30 years of his life, or Meinertzhagen places him a bit too early (note that Davey says late 19C).

This BTW shows how misleading the condition of a netsuke can be. Without the signature I would have thought your monkey to be about 100 years older than what it must be.

公鳳齋

Budget netsuke is one of my favorite netsuke topics (mostly out of necessity... With some luck and patience you can buy genuine antique netsuke even for less than 200 euro, but you need to know what you are doing to distinguish them from the 99.9% of fakes you will find in that price range. These for example I paid around 100 euro each (two on eBay, one in a flea market and one in a local auction): This one was 70 euro in a flea market: This one I paid around 100 euro at auction but it has some obvious damage:

This is a crude carving made for export in the 20th century. I would have guessed hippo tooth. It has no value to experienced netsuke collectors, but I guess someone might buy it as curio for 30-40 GBP.