Background: International immigration to Japan, where homogeneous ethnicity is a population characteristic, has been growing. Although immigration is recognized as a risk factor for multiple mental-health related issues, there are few regional reports on foreign residents who visit a hospital for mental health problems in Japan. We aimed to examine such patients’ characteristics.Methods: A multicenter retrospective study using medical records was conducted. The subjects were foreign patients who presented at the psychiatry departments in three core regional hospitals in the Keihin region, which faces Tokyo Bay and is well known to include the largest traditional industrial zone in Japan, over a period of three years. We investigated the patients’ demographic and clinical information including country/region of origin, spoken language, use of a medical interpreter, pathway to hospitals, and outcome.Results: The percentage of foreign individuals among all patients was 1.4% (205/14511). The mean age of the foreign patients was 45.8 years, and the sex ratio was 1:1.9 (men: women). Regarding the country/region of origin, China (35.1%) was the most common country, followed by the Philippines (18.5%), Korea (16.1%), and Brazil (4.9%). Several subjects (22.9%) could not speak Japanese; therefore, interpretation was required by family members/friends (17.1%) or a professional interpreter (5.4%). Neurotic disorder (ICD-10 code: F4) was the most common diagnosis (24.4%).Conclusions: The percentage of foreign patients seeking psychiatric treatment (1.4%) was relatively low, compared with the percentage of foreign residents living in the Keihin region (4.4%). The age distribution of foreign residents who visited psychiatric department was dissociated from the age distribution of foreign residents in Japan. This suggests that young foreign residents with a relatively high risk for mental illness are not accessing appropriate services. The development of a community-based integrated care system accessible to foreign residents seems to be indispensable.