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 part of the national effort by the Korean people to erase the legacy of Japanese Imperialism.
According to the Ministry of Foreign Affairs for South Korea, the name ¡®East Sea¡¯ has been used in Korea for over 2,000 years, including in History of the Three Kingdoms (1145) and "Map of Eight Provinces of Korea" (1530). On the other hand, no Japanese record published up to the late-18th century indicated any name for the body of water.
On your website, the sea between Korea and Japan is described as "Sea of Japan". But it seems unreasonable to use the name "Sea of Japan".
I think that the sea between Korea and Japan should be described as the ¡°East Sea¡± or at least with the simultaneous use of both names; ¡°East Sea/Sea of Japan.¡±