And another point about the Shinshin is that the Japanese have got the development / production sequence the right way round.
To quote wikidpaedia "The ATD-X will be used as a technology demonstrator and research prototype to determine whether domestic advanced technologies for a fifth generation fighter aircraft are viable, and is a 1/3 size model of a possible full-production aircraft"
So they're doing the research to see if it works first, before any design is fixed for production. If that had been true of the F-35, so much would be different.