I found that the sea between the Korean peninsula and Japan was labelled as the ¡°Sea of Japan¡± instead of the ¡°East Sea¡± in your title
Unfortunately, this is an error. The name ¡°Sea of Japan¡± was first used during the period of Japanese Imperialism. But the sea had been called the ¡°East Sea¡± for more than 2,000 years originally.
This fact is based on various historical evidence. The correct indication of this sea is not the Sea of Japan.
Therefore, The sea between Korea and Japan should be correctly expressed as the ¡°East Sea¡±.