Now, I would like to explain why the ¡®East Sea¡¯ must not be called the ¡®Sea of Japan¡¯.
First, the name ¡®East Sea¡¯ is historical. The term has been used for more than 2,000 years, as the first record of the name was in an ancient document titled ¡°The History of the Three Kingdoms and the Saga of King Dong-myeong¡±, which was written around 59 B.C. On the other hand, ¡®Sea of Japan¡¯ was used after Japan occupied the Korean peninsula in the twentieth century.
Second, the term ¡®East Sea¡¯ is universal. When determining the name of a sea, the most important thing is that it has to reflect the names used by the citizens of the neighboring countries. Since the ¡®East Sea¡¯ borders South Korea, North Korea, Japan, Russia, and others, it should not be called with a term that is one-sided towards Japan. In this context, the name ¡®East Sea¡¯ is suitable because it means a sea that is on the east side of the Asia continent.
Third, the term ¡®Sea of Japan¡¯ is a vestige of Japanese Imperialism. As I mentioned before, the term started to spread during the Japanese Occupation of the Korean Peninsula. Before then, it was more popular to use the name ¡®East Sea¡¯ or ¡®Sea of Korea¡¯ internationally. However, the term began to fade away because Japan forced Koreans to use only Japanese and changed the Korean names of places to Japanese style. This indicates that calling the sea ¡®Sea of Japan¡¯ is equal to supporting the cruel ethnocide that the Japanese had committed on Koreans.
Fourth, writing both terms for the sea is recommended by international laws. For example, the Technology Resolution of International Hydrographic Organization (IHO), A.4.2.6 (1974) and the UNCSGN Resolution III/20 (1977) recommend that if countries concerned fail to agree on a common name for sea, it should be a general rule of international cartography to mark both names in parallel.