This sparrow-sized bird is one of the most widespread of the world's kingfishers ranging across Eurasia and North Africa. However it seems to have declined in Japan possibly because of increased use of pesticides. This is the only one we saw. Males and females are similar but females have a mostly orange mandible. I believe this bird is a male. Seven subspecies are recognized, but only one occurs in Japan, A. a. bengalensis which is smaller and brighter cf. the European races. This species sometimes goes under the English names, River Kingfisher or Eurasian Kingfisher. Canon PowerShot SX60 HS
References:
Ali, S & SD Ripley (1987). Compact Handbook of the Birds of India and Pakistan. Edition 2. Oxford University Press.
Brazil, M. (1991) The Birds of Japan. Smithsonian Inst. Press.
Fry, Fry and Harris (1991). Kingfishers, Bee-eaters, and Rollers. Princeton University Press
Rasmussen, PC & Anderton, JC (2005). Birds of South Asia. The Ripley Guide. Volume 2. Washington DC and Barcelona: Smithsonian Institution and Lynx Edicions
Woodall, P.F. (2016). Common Kingfisher (Alcedo atthis). 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/55801 on 2 May 2016).