Question for those who know more about JAL's domestic flights: Is there a reason that the ITM-NRT route is impossible to book (with money, anyway) many months in advance? (June 22, 2020 to be specific.) Are they cancelling this route in 2020 or something? Or do they just not make domestic tickets available for purchase that far in advance?

Background: My husband and I want to take a belated honeymoon in Japan. I will book my own ticket with money, and I'll use my miles for him. Right now I'm looking at a roundtrip (paid) business class ticket that is available on Google Flights that includes ITM-NRT-SEA as the return trip, all on JAL. So apparently the ITM-NRT leg is totally bookable when it's part of an international trip. But that same leg is impossible to book on its own. It's also impossible to book ITM-NRT-SEA with my Alaska miles. So I had been thinking of just getting the NRT-SEA flight for my husband using my Alaska miles, and buying the ITM-NRT as a separate ticket. But no dice -- just can't book that domestic leg any which way. So I'm curious about whether this means the route is genuinely being dropped (doubtful, since it's still available as part of international bookings), or if it will eventually be bookable at a later date? I know that some other airlines in Asia don't make tickets available until just a few months in advance. Is that the case with JAL?