LO
I'm not sure of the relevance of your point concerning the smaller radar aperture of the F35 vice the Typhoon. If it's radar capability you are hinting at then I would much rather have the Litening IIs AESA in front of me than the Captor.
I think your point about what the Japanese want a new fighter for is much more relevant however. F35 does not really suit their requirements for a missile truck as well as some other platforms out there.
As for me, I wouldn't completely rule out the possibility of an F22 sale just yet. However, failing that I don't think the Japanese would go for the F35. They'd buy the Silent Eagle before then.