There are two species of crow in Japan. The Large-billed seemed to outnumber the smaller Carrion Crow (Corvus corone orientalis). Taxonomy is complex with 11-13 named Large-billed Crow subspecies. This is C. m. japonensis, the largest race with the most strongly ridged bill. This species was formerly called the Jungle Crow, a name now usually reserved for the smallest races, C. m. culminatus and C. m. levaillantii of India. Sibley and Monroe split Jungle Crow as a separate species, but Clements and most other authorities do not.
Some authors regard the Japanese populations, C. m. japonensis, C. m. connectens and C. m. osai as a separate species called the Japanese Crow, but a more recent study found that the latter two island races are not closely related. Madge (2019) suggests the entire complex may comprise four to seven species. More study is needed.
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References:
Madge, S. (2017). Large-billed Crow (Corvus macrorhynchos). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/60796 on 2 April 2019).
Nelson, Mike (May 17, 2013). "Vocal variation and future splits of the Large-billed Crow complex". Xeno-Canto. Retrieved 3 June 2017.