国民健康保険 (National Health Insurance) is a public health insurance system in Japan designed to provide medical coverage for residents who are not enrolled in employer-sponsored insurance. It ensures that all citizens have access to necessary healthcare services, including hospital visits, outpatient care, and preventive treatments. The program is funded through premiums paid by individuals, which vary based on income and household size. In addition to premiums, the government also contributes to the funding, making healthcare affordable for everyone. This system plays a crucial role in maintaining public health and reducing financial burdens related to medical expenses.