This chapter outlines the case of language standardization, which subsequently led to various destandardization phenomena and ludic language use. It discusses how language diversity in Tokyo has grown in recent years and how it is no longer swept under the carpet and hidden. The chapter provides a brief sociolinguistic history of Tokyo. The industrialization of Tokyo started in Yamashita along the Sumida River and then expanded northwards towards Senju. Tokyo is a popular destination for a large number of young people. The sociolinguistic history of Tokyo has been shaped by the linguistic assimilation of millions of dialect speakers under Standard Japanese. There are also three Chinese ethnic schools in Greater Tokyo today, two in Yokohama and one in Tokyo. Chinese and Korean newcomers are more proficient in Chinese and Korean than in Japanese, and newcomer pupils may receive additional Japanese as a second language instruction in the Japanese school system.