The Japanese government, in light of the lasting social and economic problems such as demographic change, economic recession, and lack of productivity, has devised policies to drive entrepreneurship and innovation. Among policies to attract potential startup founders, and as in other emerging startup ecosystems in Asia, a distinct startup visa for foreign entrepreneurs has been launched in selected Japanese cities, including Shibuya in Tokyo, but its effects are yet to be examined academically. This article uses the theoretical framework of superdiversity in order to shed light on foreigners' business ventures beyond the so-far acknowledged analytical lens of ethnic entrepreneurship and credits Tokyo's increasing socio-cultural diversity. In so doing, the article brings the often separate scholarship on entrepreneurship and migration into the conversation. It operationalizes the superdiversity framework by adopting a mixed-embeddedness approach. The analysis reveals that many foreign startup founders have lived in Japan for a long time and are culturally and socially well-integrated. Nevertheless, they engage in informal practices in the process of venturing their businesses and securing the visa status to do so, which can be explained by their limited embeddedness in politicalinstitutional terms. This article argues that not only those labeled »ethnic entrepreneurs«, who often operate in low-skilled, low-wage sectors, but also highly-skilled entrepreneurs in knowledge-intensive industries and the IT sector navigate the process of venturing a business through partial informality. A comparative examination of foreign startup entrepreneurs in Asia's startup hub, Singapore, reveals parallels in foreign founders' informal practices in both cities regardless of their ethnicity and nationality. However, the case of Singapore also demonstrates opportunities for startups founded by foreigners once they benefit from the infrastructural support of the highly-developed Singaporean startup ecosystem. The comparison underlines that despite the attention foreign entrepreneurship has received (more so in Singapore than in Tokyo), the role of informal practices in foreign founders' venturing processes is yet to be theoretically understood. The findings, therefore, point to the potential significance of both the mixedembeddedness approach and the concept of superdiversity in emerging multiethnic and increasingly diverse business ventures in the knowledge-intensive sector. The empirical findings underline the need to review immigration and startup visa policies across newly emerging startup ecosystems in Asia. [ABSTRACT FROM AUTHOR]