Japan’s English language teaching (ELT) policy has traditionally rested on the assumption that English classes are the site of “Japanese” students, “Japanese” teachers of English, and foreign assistant language teachers (ALTs). This chapter sought to understand how Japan’s ELT policy has responded to the increasing diversity of student and teacher populations in elementary and secondary education, which has stemmed from (1) the surge in immigrant student enrollments, (2) the invisible presence of local teachers from ethnic minority backgrounds, and (3) the visible presence of foreign ALTs. This chapter examined policy documents from Japan’s Education Ministry to seek references to these three groups and gauge the ministry’s commitment to enhancing diversity and inclusion in Japanese schools. Findings showed that the ministry issued student/teacher diversification guidelines and policies and continued the program that designates ALTs as cultural ambassadors. Meanwhile, ELT policy documents were characterized by an unmarked Japaneseness that legitimizes the illusory dominance of “Japanese” students and teachers. Moreover, the learning of a “culture behind English language” was relegated to a supplement to the primary objective of teaching the uniqueness of “Japanese” culture by “Japanese” teachers. This chapter further discussed future research directions for the ELT field.