PurposeAs Japan has been slowly opening up to foreign workers to supplement its shrinking workforce, local employees have had to deal with increased diversity at work, owing to the presence of foreign coworkers. This paper aims to investigate the relationship between foreign coworkers’ nationality (specifically Chinese, Korean and those from Western countries) and the perception of the benefits and threats of cultural diversity in the workplace by Japanese employees.Design/methodology/approachA sample of Japanese employees working in Japan, half of which working with foreigners, was used, focusing on those Japanese employees who reported working with foreign coworkers of a single nationality.FindingsThe authors found that Japanese workers’ perceived benefits of cultural diversity at work, but not perceived threats, are significantly impacted by the unique nationality of their foreign coworkers. Specifically, the effect of coworker nationality is most apparent for the two benefits of “understanding of diverse groups in society” and “social environment,” whereby cultural distance is significantly and positively related to these perceived benefits. And more benefits from cultural diversity at work are perceived by Japanese employees in the presence of Western or Chinese, rather than South Korean coworkers.Practical implicationsIn the Japanese context, hiring employees from certain distant and heterogeneous cultures and nationalities could increase the positive perception of multiculturalism at work, therefore facilitating diversity management and fostering inclusion in the culture of the firm.Originality/valueVery little research in Japan has examined perception biases among native employees based on the nationality of their foreign coworkers, which is critical as globally minded Japanese firms are trying to increase their level of internal internationalization.