What is up with this western notion of a 'showdown' in the East Asian theater? There will be no 'showdown' of any capacity. There are frameworks that have been established since the end of the war to ensure cooperation among equal states, which have been both summarily endorsed by both Japan and the People's Republic of China, including the Republic of China (Taiwan). The ascension of Dr. Tsai Ing Wen means a new chapter of greater collaboration between inter-states of the region. In fact, this opens the new door for Japan to bolster her relationship with China through Taiwan as conduit.
Again, to repeat, there will be no war, no showdown, no nothing of such matter. The savagery of the last war has only revealed the stupidity of East Asia fighting amongst itself, and the blood of the precious East Asian race being spilled to fuel notions of imperialism proved vanity , a foolhardy experimentation to try the western version of global order. Military adventurism for the sake of extremist thought is a chapter in my nation's history, and the blood of our collective peoples was unfortunately shed in that imbecilic experimentation. I suppose with that in mind, I share and sing with accord as other progressivist Japanese patriots --- who long for, dream for, of closer economic, political, cultural integration and union with our Racial kin and brothers --- the Chinese, and someday, long for the integration of Japan, Korea, and China in the 中文世界. The True Greater East Asia.
Pleasantries aside, on historical analysis, my friend, the Militarist Government who ruled Japan at the time merely exploited the political turmoil of China during the 1930s and the 1940s, my friend. China, since the death of Dr. Sun Yat Sen, had unfortunately been broiled in a national civil war, with various local warlords vying for regional power, as since the collapse of the Qing Dynasty, the Mandate to rule the Great Chinese Empire had disappeared. I suppose the Chinese Civil War between the Communist ideology faction on one side vying for power with the Nationalist ideology faction on one side was a natural , historical wave in modern Chinese state history. It was the national progression of state politics and the armed conflict to realize the better philosophical mandate to rule and preside over the Chinese State. In seeing this weakness during China's history, the Military Government of Japan , at the time, had taken up the same position of the Western Powers in trying to take advantage of China's political instability. We are not proud of the war in China, as it had led to the deaths of millions of Japanese and Chinese, and spiraling Japan towards the direction of oblivion, wherein the very existence of the Japanese Empire was threatened in the global pacific war that it had steered herself towards. Then again, in the spirit of positivism , and in the spirit of engaging moral soundbites, Japan , through her most 'mea culpa' of defeats and total and absolute collapse, had been reborn from her former being, and given the chance to rise as a golden phoenix , in the figurative sense. A more representative , democratic, humanistic Japan. A Japan that was an absolute 180 degree form of its former self prior to the absolute collapse and defeat in the war. Tho Japan has much to do, as i believe the nation and society has not yet fully atoned for its war time sins, the total atonement will require a cultural dynamic transformation of collaboration between Tokyo-Beijing ala Taipei.
This is why i view these developments, in context to the OP, as a natural , progression of the East Asian Cultural Revivalism. Let us be all optimistic.