F-35A can't use AAM-4, but the F-35A is going to replace the majority of Japan's fighters in the coming years. Only a small number of F-15Js will remain, probably those that underwent MSIP upgrades in the 2000s. I would imagine they would be concentrated in Hokkaido, with the F-35s going to Western Japan (which now has higher priority than Hokkaido in terms of where new equipment goes first).
Japan has its own version of the Fellas unfortunately. I would not be surprised if armed reunification was to begin and the then Japanese PM is to decline to intervene (assuming the US does too), that PM's life would probably be in danger. In 1960, when the Japan Socialist Party's leader dared to say that the US was the true enemy of both Japan and China, he was killed for that. Since then what passes for the left wing in Japanese politics has offered only weak criticism of the US-Japan Security Treaty, bases and crimes of US servicemen in Okinawa, etc.
If whoever is leading the LDP if/when armed reunification begins has the balls to choose the path to peace, it will probably splinter. It would ironically be an excellent opportunity for a left wing party to seize power, especially if influenced by other factors (worsening economy due to demographic crisis, etc.). Alas I am only fantasizing; at this time there is no outlook for such a situation.
