This study explores the enduring impact of historical memory on international relations, focusing on recent events in Northeast Asia, particularly the South Korean boycott of Japanese goods and the rise of anti-Japanese sentiment in China. It investigates why collective memories, especially those related to past conflicts and atrocities, do not fade with time but sometimes intensify, affecting diplomatic ties. The theoretical framework employs the ‘International Reconciliation Triangle’, encompassing legal, moral, and political processes. The study delves into the role of collective memory, intergenerational transmission, and the selective nature of collective forgetting. It also analyses the complex interplay between legal mechanisms, moral acknowledgment, and political leadership in fostering or hindering reconciliation. It challenges existing theories by examining the proactive role played by the younger generation in recent anti-Japanese movements, questioning assumptions about the ease of reconciliation as collective memories fade.