The country whose flag features a red circle on a white background is Japan. This simple yet striking design symbolizes the sun and has deep cultural significance. The flag is known as the Nisshoki or Hinomaru, reflecting Japan's identity and history. It’s widely recognized globally and represents the country's values, traditions, and aesthetics. The red circle, symbolizing the sun, also echoes Japan's name, which translates to "Land of the Rising Sun," encapsulating its geographical and cultural essence.