This is an adult in breeding plumage with pinkish bill and showing ornamental plumes on its nape and neck. It also has strong black neck markings of adults Birds in Japan are assigned to the far eastern race A. c. jouyi characterized by overall paler color especially the whitish face and neck as seen here. The larger Great Blue Heron (A. herodias) of the Americas is similar but has narrower black crown stripes and usually, but not always, chestnut-brown flanks and thighs. Canon PowerShot SX60
References:
Ali, S & SD Ripley (1987). Compact Handbook of the Birds of India and Pakistan. Edition 2. Oxford University Press.
Hancock, J. & H. Elliott (1978) The Herons of the World. Harper & Row
Martínez-Vilalta, A., Motis, A. & Kirwan, G.M. (2018). Grey Heron (Ardea cinerea). 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/52674 on 14 August 2018).
Palmer, R. (1962) Handbook of North American Birds, Vol 1: Loons through Flamingos. Yale Univ. Press.
Rasmussen, PC & Anderton, JC (2005) Birds of South Asia. The Ripley Guide. Vols. 1 and 2. Smithsonian Institution & Lynx Edicions, Washington, D.C. & Barcelona