Yamada Motonobu, who lived from 1847 to 1897, was originally, like many of the finest Meiji-period metalworkers, a retainer of the Mito branch of the Tokugawa family. He moved to Edo in about 1872 and is recorded as working for the Imperial household in 1877; he was also commissioned by the Ozeki Company.1 The Mount Akiba referred to in the signature is not the peak of that name in Aichi prefecture but an elegant locution for the district of the Akiba Gongen shrine on the banks of the Sumida river in Edo, an area where several Mito metalworkers resided.2 For a very similar example of a spherical iron koro by the same artist, see Joe Earle, Splendors of Imperial Japan: Arts of the Meiji period from the Khalili Collection (London, 2002), cat. no. 112, with a design of the twelve Zodiac animals.
1 Robert E. Haynes, The Index of Japanese Sword Fittings and Associated Artists (Ellwangen, Germany, 2001), p. 1174 (05904.0) and Oliver Impey and Malcolm Fairley (eds.), The Nasser D. Khalili Collection of Japanese Art (London, 1995), vol. 2, part 1, cat. nos. 51-2, 55, 60 and 72.
2 Paul Waley, Tokyo Now and Then (New York and Tokyo, 1984), p. 256.