日本は成果物（戦闘機）のほとんどの（開発・製造の）権利を手に入れる
https://www.defense-aerospace.com/uks-tempest-flying-technology-demonstrator-program-stealthy-in-shape-and-execution/

Now, there's some way to go as regards Tempest – the UK name for whatever comes out of GCAP, although it is likely that Italy will be in lock step with the UK, and Japan will take much/most of the resulting work – but, jeez, the pace to date as revealed has been pretty impressive!