fumitani, thanks for your willingness to help. I now have the official answer from ANA.
I wanted to fly to a domestic destination in Japan and then have a stopover in Tokyo at the end of my visit. I cannot do that. I had to ticket one way to the domestic stop, then one way from Tokyo back to the US. I will have to buy the internal flight from the domestic city to Tokyo separately from the award ticket.
Trying to find a different way to say it, I am allowed an open jaw award but I cannot have a RT award with a stopover at the gateway city.