It is a complicated issue. Most certaintly, the governments of both south korea and china have relied on anti japanese nationalism to distract their people from domestic issues.

The majority of chinese and korean people alive today did not directly experience japanese imperialism. And, if they went to public schools in their countries, they probably learned a lot about japanese atrocities and very little about the postwar reparations/oda payments from japan or the apologies from japan. The domestic media in their countries highlights a minority of unapologetic japanese nationalists. It isn't surprising that they end up still angry about events that occurred before they were born.

I am on my phone now, but i recommend books on history issues by by sven saaler and philip seaton.

Edit: Book titles to check out.

• History Textbooks and the Wars in Asia: Divided Memories (Gi-Wook Shin)
• Japan's Contested War Memories (Philip Seaton)
• Politics, Memory and Public Opinion. The History Textbook Controversy and Japanese Society. (Sven Saaler)
• The Making of the "Rape of Nanking": History and Memory in Japan, China, and the United States (Takashi Yoshida)