Apologies for resurecting an oldish thread, but I have just managed to discover how to do this online at ba.com. I have also been trying to book a one way HND-HIJ on JL for next March, but when I entered it on to ba.com it comes up with the error that "British Airways and its partners do not fly this route". I think that is because there is some kind of 60 day limit in play for booking domestic JL flights.

However, I tried entering a date much sooner (13/10) which did bring up a list of flights. Then I kept clicking on the "next week" tab to advance forward with dates until I got ot the date I wanted in March. A list of flights was now displayed and I just selected the one I want and bought with avios as usual.

Result is award in Y HND-HIJ for next March at £1.10 + 4500 avios as opposed to the JL cash fare which was £220.




The JAL MMB site is here btw, but you can't seem to select a seat until 2 months out.