Hello,
I have dealt something with the part.
I have no idea, therefore, I have asked in Japan a coin trader.
here his answer:
I have never seen this.
1) I think this is not a money/coin. >> but a local/regional
money ? >> I have not seen on auction catalogues.
2) I can not say nothing on the material >> seems to be gold ? >>
it is a golden color, but we need an mechanical examination.
3) The letter is japanese and may be from Japan. No information who
made ? for what ? >> no original sample.
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Hence: the piece is unknown in Japan....
My opinion an imagination amulet. The characters are Japanese, however, The signs are Japanese, but they have no meaning.
Greetings from good old Germany

pingu