Background: Migration and place of birth are increasingly recognised as social determinants of health among sexual minority populations. Among men who have sex with men (MSM), being born outside the country of residence may shape access to healthcare, community resources, and social capital networks. In Japan, however, little is known about how being born outside Japan is associated with social capital, health behaviours, and mental health among MSM. Methods: Data were drawn from a large cross-sectional online survey conducted in 2025 of 8150 MSM living in Japan, recruited via community-based in-person outreach and targeted geo-social networking application advertisements. Multivariable logistic regression analyses examined associations between country of birth and social, behavioural, and health-related outcomes. Results: Foreign-born MSM were younger and more concentrated in the Greater Tokyo metropolitan region. Being born outside Japan was associated with higher odds of HIV testing across all timeframes and higher levels of both gay and heterosexual social capital. Foreign-born MSM were also more likely to have disclosed their sexuality to friends and family. However, they were less likely to be aware of LGBT or HIV prevention organisations, despite higher participation once engaged. No differences were observed in suicidal ideation or unprotected anal intercourse with casual partners, although foreign-born MSM were more likely to report unmet need for mental health care. Conclusions: Foreign-born MSM in Japan demonstrate strong engagement in HIV prevention and higher social capital, alongside persistent barriers to community awareness and mental health service access. These findings highlight the importance of addressing structural and informational barriers and supporting community-based organisations to improve equitable health and wellbeing outcomes among MSM in Japan.
Hill et al. (Wed,) studied this question.