Truely a crappy photo but i think i can see the black cap, the white wingspot and the less clear greyish spot.
http://www.pbase.com/image/133299210
Unfortunately it flew off before i could take another shot. I don't think I have a proper photo. Only a recording.
Japanese name: tobi, or tonbi, トビ / トンビ.
Record on eBIrd
Three male Harlequin Ducks paraded along the shore