It seems extremely inappropriate and frankly appalling, that an educational site would be so ill informed to blatantly use of such designation with complete lack of regard for the dispute between the two countries. Your site should educate not spread misinformation.

Using the proper name for the body of water between Korea and Japan is not simply a question of naming a geographic area but is part of a national effort by the Korean Republic to erase the legacy of Japanese Imperialism and to redress the unfairness that has been resulted from that period. The way African-Americans were enslaved, so was the Korean people.

Therefore, I urge you to use 'East Sea' to describe the body of water in question or to use both Korean and Japanese designation simultaneously  in your contents and maps.