Its not a coin. It is a Japanese souvenir, very similar to what you would get from the Perth mint gift shop.... ( Make your own coin) @ the Perth mint type thingies.
Yes its Japanese shown by the chrysanthemum on the reverse of the coin above which is 5, 5 Sen(5 Cent) its not a mint your own thingie from the gift shop but i like the call and about as valuable but more intresting, (1941 Yr 16 i think) many were brought back from WW11. the earlier( to 1917) 10 sen coins & up were silver.