By applying an online ethnography of Japanese youth language practices on social network services (SNS), the present research explored the young adults’ translingual repertoire, in which linguistic and non-linguistic semiotic resources are interwoven. The researcher conducted an extensive period of online observation of Instagram, questionnaire surveys, and multiple semi-structured interviews. The analysis illustrates their capability to exploit their available linguistic resources, including English, Japanese, Chinese, Korean, Portuguese, and German. They utilized these languages not only due to their comfort but also because of their desire to exhibit their local identities or express intimacy to their potential target audiences of numerous followers. Their language practices demonstrate their intricate identity formation in an online space where geographical boundaries transcend. Furthermore, they utilized diverse semiotic resources, including photographs, emojis, and hashtags intertwined with “named” languages. Their online language practices question conventional formal categorizations of what language is.

Furthermore, the interview revealed that their online practices are intertwined with their offline experiences, including their friendships, language experiences, and language ideologies spread in the domestic society. For example, their language practices reflect linguistic beliefs such as language as an emblematic role and an asset to thrive in globalization. Furthermore, the participants are constrained by language prescriptivism, constructed through personal experiences, such as the entrance examination.

The present research sheds light on translingual practices by Japanese youth, which has received limited attention by embossing the Japanese participants’ capability of using their repertoire ad hoc in an online space to express their translocal identities. Furthermore, it shows a complex interrelationship between their online language practices and their offline experiences and beliefs associated with languages.

The research progress and outcome were/will be presented in the following academic conferences as an individual or co-authored papers: IAWE (International Association of World Englishes) in New York, U.S. in June 2023; Asia TEFL (Teaching English as a Foreign Language) in Daejeon, S. Korea in August 2023; JACET (Japan Association of College English Teachers) ELF SIG International Workshop in Tokyo in January 2024; Youth Media Conference in Vienna, Austria in March 2024; AAAL 24 (American Association of Applied Linguistics) in Texas, U.S. in March 2024. Two chapter contributions (one co-authored) to edited books, published from Akashi Shoten and DeGruyter respectively, are current in press.