Whether or not it is fake, it seems to me to have been written by someone with some knowledge of the Chinese characters, rather than by someone just imitating them.
I cannot decipher the first character, but the remaining characters appear to be:
邑 熊 恒 泰 自 造, although I am not certain about the third one (恒).
The inscription strikes me as most likely being Chinese (or possibly Korean), but not at all likely to be Japanese. The meaning of the final two characters together is "self made", suggesting to me
that an earlier part of the inscription includes a person's name. Perhaps that name is
熊恒泰.
That is the best that I can do.