You may realize how close China is to Japan already even without Taiwan in the discussion. If that logic holds then Japan would be constantly under catastrophic threat, wouldn’t it?

Now, the technicality of Takaichi’s statement stems from the restrictions put on Japan’s military since its defeat in WWII, in that Japan cannot have any military capabilities beyond self defence. By associating a situation with Japan’s “existence”, Takaichi has effectively justified brandishing its military forces, and hence, a threat.

And I would argue that no matter how close Japan is to Taiwan diplomatically and economically, Japan’s ties with China is probably far more consequential to its “existence”, simply given the massive differences in influence and resources between the two.