The national flag of Japan has an overall white background with a large red circle in the center. Nisshoki (literally, Rising-Sun Flag) was adopted as Japan's national flag in 1870. It also is called Hinomaru (literally, Disk of the Sun) and Nihon no Kokki (Flag of Japan). However, the flag was not adopted nationally until August 13, 1999. The shape and flag ratio of the Japanese flag is described as 2:3 ( length 1½ times the height ). The sun, a circle centered on the flag, has a diameter of 3/5 the width. (The sun actually is positioned 1/100th the length closer to the pole edge of the flag.)
Meaning of the Japanese Flag
According to the Britannica Encyclopedia, the sun goddess Amaterasu founded Japan in the 7th century BC and was an ancestor of the first of its emperors, Jimmu. Even today the emperor is known as the “Son of the Sun,” and a popular name for the country is “Land of the Rising Sun.” The characters which make up Japan's name mean "sun-origin", which is why Japan is sometimes identified as the "Land of the Rising Sun".
The red circle represents the sun.