Zainichi Koreans are the descendants of colonial subjects who migrated to Japan from 1910 to 1945, when Korea was part of the Japanese empire. In 1952, the Japanese state stripped them of their nationality status and left them stateless. Like racial minority groups in other societies, Korean descendants still face systemic discrimination in contemporary Japan. Although they were colonized by a non-European power and are not physically distinct from the dominant Japanese population, their situation is often compared to that of African Americans. Yet, for scholars who think that race is necessarily based on “phenotype,” anti-Korean oppression cannot qualify as an instance of racism in Japan and the comparison with Black Americans is misguided. This article explores the intellectual and political issues at stake in debates over the use of racial comparisons—what I call the “racial politics of comparison.” Examining the views of scholars and Zainichi Korean activists, I show how the latter have drawn inspiration from the Black liberation struggle and built alliances with African Americans in order to resist oppression. I argue that their unique situation forces us to revise the role attributed to phenotype in current definitions of race and racism.