This research examines the failure of Japanese whale diplomacy following the International Whaling Commission’s (IWC) moratorium on commercial whaling in 1986, with a focus on Japan’s attempts to change the conservationist view of whales to the one focused on consumption of whale meat. This article explains how Japanese whale diplomacy attempts to convince the international public that whaling is part of cultural preservation. The method used is a qualitative approach with analysis of official government documents and research related to Japanese diplomacy and whaling. The constructivism approach was used to analyze how international identities, norms, and discourses shape Japan’s diplomatic policies.The findings show that, despite Japan’s efforts to prove that whaling is safe and sustainable, it has failed to change international norms on whale conservation. The dominant international discourse continues to regard whaling as unethical and environmentally damaging. Significant resistance from other countries that support conservation was a major obstacle.This research reveals that the failure of Japanese diplomacy was not only due to international resistance, but also Japan’s inability to align their scientific and cultural arguments with a global narrative that prioritizes environmental ethics. The contribution of this research lies in understanding the dynamics of norms and identities in international relations and the importance of ethical narratives in environmental diplomacy.