Vaccination status does not matter. Where did you get the idea that the Japanese government, airlines or airports have any requirement for transit passengers?
The CDC site has been updated. 「This rescission takes effect for flights departing to the United States from a foreign country at or after 12:01am ET (4:01am GMT) on June 12, 2022, and will be published in the Federal Register」
Getting ridiculous. Airline CEOs are pleading to Washington. I think the Delta guy said like 45 out of the 50 counties they fly to don’t require tests. And yes, you can fly to Canada and drive to US. No test.