The answer is yes to both of your questions. As a US citizen you are required to report your worldwide income from any source, and that would include the rental properties you now have in Japan.
And yes, you would need to file a form 3520 to report the inheritance that you received from your aunt. The reporting requirements for a US citizen living abroad are the same as if you were living in the US. I am giving you a link below which summarizes some of those requirements, including the need to file a form 3520.
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