> Japan and South Korea are commonly treated as being part of the West for the same reason Australia is

Australia isn't "treated" as being part of the West. It is a western nation. It's people, institutions, culture, language, etc are all of western origin. Japan and South Korea are not western nations. All you would have to do is go ask the japanese or south koreans themselves. I don't know of anyone who "treats" Japan and South Korea as western nations except those with a bizarre agenda.

> they are geographically in Asia but aligned with the United States and EU.

Australia would still be a western nation even if australia was aligned with china. Also, western nations existed before the EU and even before the US were created. If the US and Australia went to war against each other, they would still be western nations.

> And China initiated the trade war with Japan all the way back to the Senkaku Diaoyu standoff.

Then you might as well argue Japan initiated the trade war by imperial expansion to those islands.