Strategic human rights litigation aims to seek for significant changes in law and policies, or influence public opinion and awareness, through situating individual client interests or human rights within larger social goals, or creating progressive jurisprudence, which advances human rights and rebalances the historic or systematic injustices. However, the law and society debate over litigation and social change sheds light on both the positive and the negative sides of strategic litigation. On the one hand, the positive view emphasizes that strategic litigation can change social understandings and create issues around which to organize a movement by attracting publicity, media attention and participants to a movement. On the other hand, critiques point out the limits of individual litigation as a strategy for social change and even its negative effects, arguing that legal victories bring no real change and individual litigation can narrow issues and atomize collective grievances, undermining broader collective action. In light of this debate over strategic human rights litigation and social movement, this article explores the role of the recent hate speech and hate crime cases in Japan, in which an elementary school for residential Koreans in Kyoto was raid by xenophobic nationalist groups in 2009 and 2010. These Kyoto Korean School incidents were part of the growing racism and ultra-nationalistic campaigns against ethnic minorities in Japan, in particular, against those who reside in Japan with Korean descent. This empirical socio-legal analysis examines the Kyoto Korean School cases in the dynamic process of the anti-hate speech and racism movement in Japan as an example of successful strategic human rights litigation, aiming to propose a broader framework through which we understand strategic litigation, focusing on the interaction between domestic and international laws and advocacy by civil society. This study has shown that the Kyoto Korean School cases had an enormous positive impact on the anti-racism movement in Japan including raising consciousness among the plaintiffs and public awareness without a big backlash and led to the enactment of the very first anti-hate speech law and a municipal ordinance, with the support of increased media attention and public opinion against hate speech. In this case, those effects were not originally pursued, but grew out of not only the judicial decisions but also of the process for seeking justice, thus calling the cases “unintended strategic litigation.” It was a transformative process for both plaintiffs and lawyers, namely iterative and interactive process of human rights norms diffusion, rather than top-down. This paper also analyzes the reasons behind this “success.” The rulings of the Kyoto Korean School case, which condemned hateful demonstrations as “racial discrimination” under the international human rights convention, framed the issue as the matter of universal concern which affects Japanese society as a whole. The rulings were accepted by the majority in Japanese society without inducing the backlash. Unprecedented application of the international human rights convention was highlighted by media, while some extreme characters of this hate crime case against elementary school children also attracted media attention. This brought the long-standing efforts of civil society groups and activists to vernacularize the universal human rights norms into the attention of majorities, which has been spread in Japanese society with the historic effort of civic networks of diverse actors, not only of lawyers but also of civil society organizations, local communities, and a massive number of individuals who joined in counter-movement. It pushed a majority of the society into major actors of the expanding anti-racism movement and also brought the Kyoto Korean School cases, its process of proceedings, and the subsequent results to domestic and international attention, with a help of the Internet media. In this sense, the recent anti-racism movement in Japan is not only a leftist elite or professional activist movement but also involves general public and local community members connected loosely via the Internet. The combination of the bottom-up human rights movement based on the locality and the international and national advocacy of leftist groups engaging lawmakers have provided an impetus in advancing legal development against hate speech. The culmination of activists’ efforts, in collaboration with policymakers and human rights workers with the support of public opinion, came in May 2016, when Japan passed its first law against hate speech. Consequently, this analysis shows the Kyoto Korean School cases were successful as unintended strategic human rights litigation since the multiple stakeholders brought a universal human rights ideology embedded in the rulings into a wide range of communities in society in a dynamic process involving diverse actors including lawyers, civil society organizations, local communities, individual activists, journalists, lawmakers, and even international human rights organizations, where the purpose of social movements is complemented by legal means.