Often called "Common Kestrel," this is a female. Males are similar but redder above and a have a bluish crown and tail. As in most birds of prey, the male averages smaller than the female. This is sometimes called "reverse sexual size dimorphism," a phrase which strikes me as inherently biased in its assumption that males should be larger. The population breeding in Japan is said to average more heavily marked than those in Europe, but subspecies differences are slight. Digiscoped with Panasonic Lumx LX5 | Nikon Fieldscope III | 30X hand-held no adapter.
References:
Global Raptor Information Network. 2019. Species account: Common Kestrel Falco tinnunculus. Downloaded from http://www.globalraptors.org on 30 Mar. 2019
Orta, J., Boesman, P. & Marks, J.S. (2019). Common Kestrel (Falco tinnunculus). 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/53213 on 30 March 2019).