Earlier quoted context omitted.
Japan's self-defense force is better-equipped, I will grant, but there are a few reasons. One is that there is always a higher level China could escalate to. I mean, in the end game they have nukes and Japan doesn't. But even if it didn't get to that level, China is a totalitarian regime with a history of brutally suppressing dissent, and I also assume that China would be willing to lose a lot more lives to make gain…
Japan may not officially have nuclear weapons, but they do not lack the capability - if they decided to weaponize (which would never happen short of a Chinese existential threat), they could do so in a matters of days, not months - the nuclear knowhow is clearly there. The rest of your point is fair - for Japan to go to war would take a fundamental shift in the country, and its questionable whether the Senkaku Island…
You don't make nuclear weapons in days. Unless you have no idea what you are talking about. Weapon grade uranium takes months to produce. Why do you think Iran has been trying for so long to make such material ?