Zainichi Koreans, whose ancestral migration resulted from Japan’s colonization of the Korean Peninsula (1910–1945), are a culturally assimilated minority group now showing accelerated structural assimilation through naturalization and intermarriage with the Japanese majority. Nonetheless, since the mid-2000s, internet-mobilized right-wing activists have deployed hate campaigns against Zainichi Koreans or institutions they label as ‘anti-Japanese’. Conventional Zainichi Korean organizations, the pro-Democratic People’s Republic of Korea (DPRK) Chongryon and the pro-Republic of Korea (ROK) Mindan, have never formally collaborated to respond. Drawing on fieldwork (2011–2016) and secondary sources, this article explores factors that maintain fragmented ethnic advocacy. Focusing on Zainichi organizational responses to three hate incidents in Kyoto and Tokyo, I examine four dimensions: (a) preceding inter-organizational relationship, (b) bureaucratic inertia, (c) discordant framing strategies, and (d) external socio-political conditions. Organizational stances differ not just by pledged allegiance to different Korean nation-states, but also by organizational response to Japanese policy-making and the legislature. While both organizations adopt framing strategies based on the universal norm of human rights, Chongryon emphasizes minority education rights and Mindan problematizes hate speech per se. I argue that the contrasting strategies reflect broader socio-political factors more than organizational characteristics. Heavy reliance on the Japanese majority as the target audience maintains a fragmented Zainichi Korean advocacy.