Using a proper name for the body of water between the Korean peninsula and the Japanese archipelago is not simply a question of changing the name of a geographical feature. It is a part of the national effort by the Korean people to erase the legacy of Japanese Imperialism and to redress the unfairness that has resulted from it. It is an absolute mistaking to hear just one side of story and to blindly follow. If we leave these kinds of things alone, it causes serious problems that disturb the order of International society.
For your reference, National Geographic, the world's largest commercial mapmaker, worldatlas.com,the world's largest commercial mapmaker, and the travel guidebook, Lonely Planet Publication, promised us that they would now use the name 'East
Sea.' In addition, National Geographic and Lonely Planet are already using the name, 'East Sea' on their website after we pointed out the error.
http://prkorea.com/textbook/reference2.htm