Formerly considered conspecific with similar Common Buzzard (Buteo buteo) but genetically highly divergent and now generally considered a separate species. Sometimes called Japanese Buzzard, its voice is reportedly different. Like Common Buzzard, this species is highly variable, occurring in light, dark and intermediate morphs. I believe this individual is an adult based on blurry upperpart pattern and short tail. Three subspecies usually recognized with this being the widespread nominate race. Two smaller races, one of which is probably extinct, are confined to islands in southern Japan. Canon PowerShot SX60.
References:
del Hoyo, J., Collar, N., Marks, J.S. & Kirwan, G.M. (2019). Japanese Buzzard (Buteo japonicus). 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 https://www.hbw.com/node/467356 on 2 May 2019).
Global Raptor Information Network. 2019. Species account: Eastern Buzzard Buteo japonicus. Downloaded from http://www.globalraptors.org on 2 May. 2019