I imagine that if you booked the ANA onward connection, and happened to miss it, ANA agents would be more sympathetic to reaccommodating you without penalty given that you arrived with their international flight.
AirDo you would have no excuses / they would be within rights to not help you above and beyond what the rules call for.
Maybe this is a factor to consider.
Maybe, though AirDo is part of ANA so it might not be a big problem.