Your coin is Japanese and appears to be a Kan'ei tsuuhou. The mintmark is from the Kamedo mint. The diameter should be 25 mm. This link should help you further:-
http://www.history.ucsb.edu/faculty...pancash.html
or you could purchase a copy of Early Japanese Coins by David Hartill
http://www.history.ucsb.edu/faculty...pancash.html
or you could purchase a copy of Early Japanese Coins by David Hartill




















