You should honestly consult a tax professional about this, as it's not a good idea to get tax advice from strangers on the internet. But according to the IRS,

You should honestly consult a tax professional about this, as it's not a good idea to get tax advice from strangers on the internet. But according to the IRS, you are only taxed at time of disposal when capital gains were realized. I am not at all familiar with Chinese or Japanese tax law, so I couldn't tell you what your liabilities might be there.