This is why some neighbors of the host country have called for the flag to be banned at the Tokyo Games which begin Friday.
It is unlikely that the ties between Seoul, Tokyo and other countries will improve anytime soon. The flag dispute could be resolved. Experts believe that the COVID-19 restrictions, which have prohibited spectators from most Olympic venues stadiums, may help to prevent further disagreements.
Here's a look into the "rising Sun" flag and the unease that it has caused for Northeast Asia.
Japan is associated with two rising sun flags, which in Japanese mean "the sun's source".
One is the national flag of the country, also known as "nisshoki" or "hinomaru", which features a red circle on a background of white. This is a common design.
Another one has a red disk, but is surrounded with 16 rays that radiate outward. This one is called "kyokujitsuki" and has been the subject of vehement protests by some of Japan's neighbours.
Both flags have been in use for centuries. The early 20th century saw disputes over the "rising Sun" flag. It was then that Japan's imperial navy used the flag to colonize the Korean Peninsula, invade or occupy China and other Asian countries until it lost World War II in 1945.
It is still Japan's Navy Flag, used by both the Maritime Self-Defense Force (in a modified version) and the Ground-Self Defense Force (in a slightly modified form) since 1954.
Ultra-rightists in Japan use the flag a lot these days during rallies and on social media.
Japan's government stresses that both rising sun flags feature the sun as a motif. They were used throughout the country long before World War II. According to the government, the rising sun with its rays flag motif can still be found in Japanese daily life, including celebrations of big fisherman catch, childbirth, and other festivities.
It doesn't matter if it is a symbol of militarism or a political statement. "I believe there is an enormous misunderstanding," Yoshihide, the Japanese Prime Minister, stated in 2013. He was chief cabinet secretary.
Japan's neighbours see it differently.
South Korea requested in 2019 that the International Olympic Committee ban the flag from the Tokyo Olympics. Seoul stated that the flag recalls "scars" and "pain" of Asians who suffered wartime aggression by Japan. This is similar to the way the swastika reminds Europeans about the horrors of World War II.
The state media of North Korea, which are not known for their understatement, has accused Japan of trying "to turn the flag of war criminals into a symbol to peace at the Olympics," saying that it is an "intolerable insult to our peoples and other Asian peoples."
China also reacts very sensitively to any perceived insults from the Japanese government or individuals. Official outrage about history has decreased somewhat. However, China's political and economic rivalry with the United States has grown in recent years. The flag is clearly more sensitive in China than it is in South Korea when it comes to flags.
USE AT THE GAMES
Seoul claimed that it had received an IOC promise from the IOC that the display of the "rising Sun" flag at other Olympic venues would be prohibited.
South Korean media reported later that activists had carried the "rising Sun" flag near the athletes’ village. According to media reports, the flag was not banned in Olympic stadiums by Japan's organizing committee.
Professor at Ewha University, Seoul, Leif-Eric Easley stated that it would not be appropriate to ban the flag from the naval exchanges, as a Japanese Maritime Self-Defense Forces uses a similar version. You wouldn't expect the Tokyo Olympics hosts to use the rising Sun emblem, nor would you expect Japanese athletes to use it. It is not the country flag.
The U.S. allies have had long-lasting difficulties with their ties to Seoul and Tokyo as a result of trade and history disputes.
Moon Jae-in, South Korean President, announced Monday that Moon would not visit Japan for the Olympics due to insufficient common ground between the two countries to support a summit of leaders.
WILL IT GET BETTER?
Experts say that the flag dispute is not as important as other points of contention like Japan's wartime mobilisation of Koreans into forced labor or sexual slavery. It won't likely cause any further tensions.
However, the flag dispute could still flare if anti-Japanic civic groups in South Korea provoke a backlash from the Japanese public, according to Lee Myon-woo (deputy head of the private Sejong Institute near Seoul). Lee said South Korea should not give the flag a "too extreme, political interpretation" because Japan has no indication of reviving its past militarism.
Bong Youngshik is a researcher at Yonsei University Institute for North Korean Studies and says that the flag would not have been a major problem if Japan had made a more sincere apology for its wartime abuses.
The dispute may not have enough fuel to keep it going, but there is one reason. There aren't many people at all Olympics venues, so no one is waving the flag, which could mean that the dispute may end for now.