I flew LAX-HND on “proper” NH last month and HND-SYD on Air Japan. They were indistinguishable in just about every respect. You can see the “Air Japan” logo near the tail on those aircraft but otherwise fully branded as ANA. There was no indication inside the airport at all that there as any difference. As noted above, I think the absolute only change onboard was the amenity kit; but everything was available in the lavatory or from the FAs anyway.