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. "Handbook of Birds of the World" suggests the entire complex may comprise up to seven species. More study is needed. Canon PowerShot SX50 HS.
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 4 June 2017).
Nelson, Mike (May 17, 2013). "Vocal variation and future splits of the Large-billed Crow complex". Xeno-Canto. Retrieved 3 June 2017.