Originally Posted by ernestnywang

Routes between Okinawa and rest of Japan are well served by JL. Both CX and JL fly between Taiwan and Tokyo, Osaka, and Nagoya. You certainly don't need to step outside of oneworld if these are the excursions you are considering.

If you are just considering breaking a long-haul between the UK and Japan into 2 medium-hauls, within oneworld I can't think of anything else other than QR, many of whose fares do allow free stopover in DOH.