The Asian country whose flag features a red circle on a white field is Japan.
Japan’s national flag is a white rectangle with a centered crimson disc representing the sun. Its official Japanese name, Nisshōki, means “flag of the sun,” while Hinomaru, or “circle of the sun,” is the name most commonly used in Japan. The design reflects Japan’s traditional image as the Land of the Rising Sun.
The sun has deep importance in Japanese history, mythology, and religion. In Shinto tradition, the imperial family is linked to Amaterasu, the sun goddess. Historical records describe sun imagery on a Japanese court flag as early as 701, although the modern flag became especially prominent during the Meiji period.
The red disc flag was used for merchant ships from 1870 and functioned as Japan’s de facto national flag long before legislation formally designated it. Japan’s Act on National Flag and Anthem made the design official on 13 August 1999. It should not be confused with the Rising Sun military ensign, which adds radiating rays.