Just wanted to provide an update to this post. As of today, you can still transit NRT on separate tickets and ANA will still through check to UA. Let ANA check you in for UA flight rather than doing self check in, since they might need to make adjustments when through checking and linking reservations.

Of course, if you can book single tickets, please continue to do so as it saves the hassle at check-in. I’m sure many who are doing separate routings are redeeming VS on ANA. I can’t report on other outstations but ANA staff at ORD seem to be familiar with the routine.

Also, even though technically required, airlines haven’t been checking COVID tests for passengers entering Guam when transiting Narita and originating in the CONUS, regardless if it’s separate or single itinerary. Please don’t take this as a recommendation to avoid a test, but if for some reason you can’t get a test in time, the enforcement seems to be questionable on CONUS-NRT-GUM routings.