Why is there a red dot in the middle of the white flag of Japan?

The red circle of the national flag symbolizes the sun. The national flag of Japan is called the Hinomaru, which comes from the Japanese word "Sun Maru", which literally means "Sun Circle". It is uncertain when the symbol of the sun circle was first used on flags and slogans. However, in the 12th century, samurai appeared. In the struggle for power between Minamoto and Taira, samurai liked to draw the sun circle on a folding fan (called gunsen in Japanese). During the Warring States Period in Japan in the 15th and 16th centuries, many military figures fought for spheres of influence, and the symbol of the sun flag was widely used as a military emblem. A folk craft screen painting depicting the battle in Guanyuan in 16 depicts an army, and many of its military flags have the basic color of the sun flag. Although white background with red circle is the most common, there are also dark blue background with gold circle.

The sun circle flag is hung on the ship carrying the shogunate, and Hinomaru is used as a symbol representing the whole country. Its history can be traced back to Toyotomi Hideyoshi in the late 16th century and Tokugawa Ieyasu in the early 17th century. A screen depicting the scene of Edo (Tokyo today) in the 17th century shows that a sun flag is used as a symbol to indicate that the ship carries a shogun. During the "Lock-up Period" (1639-1854), foreign trade and other relations with China, Korea and the Netherlands were prohibited. However, when the Tokugawa shogunate began to trade with other countries (including the United States and Russia) after 1854, Japanese trading ships began to use the sun flag again. In 1854, the Tokugawa shogunate accepted the suggestion of a man named Shimazu Nariakira in Satsuwa (now Kagoshima Prefecture), and decided that Japanese ships would use the "sun flag on a white background" to avoid being mistaken for foreign ships. In 186, the official ship Kanrin Maru, which sent Japanese officials to the United States, was hung with the sun flag. After the Tokugawa family lost their political rights, the Meiji government was established in 1868. According to Decree No.57 issued by the Grand Council of State on January 27th, 187, the Sun Flag was officially designated as the Japanese flag used on commercial ships. In 1872, the year before the solar calendar officially replaced the lunar calendar, the sun flag was first used on the site of government buildings. At that time, many ordinary families and non-governmental organizations also expressed their desire to hang the sun flag on holidays. In later years, many notices and documents were published publicly, which strengthened the status of the Sun Flag as a symbol of Japan.