The Japanese flag represents the sun, according to Famous Wonders. The flag consists of a plain white field with a red circle in the center. The red circle is representative of the sun since Japan is one of the first countries to see the rising sun.
In Japan the flag is formally called “Nisshoki,” which means “sun-mark flag,” and it fits with Japan's nickname, "The Land of the Rising Sun." Famous Wonders states that the Japanese flag was officially adopted as the national flag in 1999, although the symbol of the “hinomaru” or “sun disc” had been used since the early days of the samurai.