I would like to dissect your post if I may.

Unlike in post-war Germany, the Japanese government has never assumed any public responsibility for the atrociries committed by the Japanese army before and during WW II. Germany has apologized, Japan never did. BTW, it is not only with respect to China but also with respect to Korea.

https://en.wikipedia.org/wiki/List_of_war_apology_statements_issued_by_Japan

1957: Prime Minister Kishi Nobusuke said to the people of Australia: "It is my official duty, and my personal desire, to express to you and through you to the people of Australia, our heartfelt sorrow for what occurred in the war."[7]

September 29, 1972: Prime Minister Kakuei Tanaka said to the people of the People's Republic of China: "The Japanese side is keenly conscious of the responsibility for the serious damage that Japan caused in the past to the Chinese people through war, and deeply reproaches itself. Further, the Japanese side reaffirms its position that it intends to realize the normalization of relations between the two countries from the stand of fully understanding 'the three principles for the restoration of relations' put forward by the Government of the People's Republic of China. The Chinese side expresses its welcome for this" (Joint Communique of the Government of Japan and the Government of the People's Republic of China).[8]

The difference is, that countries like the UK are mature enough to not continually demand apologies from places like Germany and Japan and are able to "move on". I believe with the Chinese it is nothing more than nationalism being stirred up by the CCP to maintain their legitimacy and the majority being so brainwashed by into it. In Nanjing there is a holocaust type museum bemoaning all the Chinese who died, but failing to mention they were locked inside, by guess who, Chinese. 3 million dead, or 60-80 million dead by Mao Zedong? The difference is in Romania, they executed their former dictator, in China, they honour him with a mausoleum in Beijing....it boggles the mind?!