My Japanese attorney says JP taxes won’t be affected by Roth IRA Investment, is this accurate?

I ask because he is Japanese and mostly works either Japan only clients so while I did double check with him, noting the Roth ira is (by US standards) a tax free retirement investment portfolio, he said I shouldn’t have to worry about reporting it in terms of income for Japan at all. Do you think this is fully accurate?

EDIT: took someone in this threads advice to ask what the basis of his statement was, and he apologized to me saying it turns out I’d have to report once I inevitably withdraw from the account. Now I am wondering what to do financially….