The sea between Republic of Korea and Japan is called by two names worldwide. 

East Sea and Sea of Japan.

The former name is from Korea and the latter name is from Japan. 

The most important rule in naming the sea is to look back at the names commonly used by the people of neighboring countries. East Sea appeared in history more than 2,000 years ago and has been used on the peninsula ever since.

The first records of " East Sea" are in "The History of the Three Kingdoms" and "The History of the King of Dongmyung," and " East Sea" appears in the process of recording around 59 B.C. It is also known that Japan used the country name Sea of Japan about 700 years later. The East Sea, which borders Japan and Russia starting with the Korean Peninsula, is not only a sea of Japan but also a sea shared by many countries. Therefore, Japan's unilateral view of Sea of Japan is not correct.