I can tell you that the name east sea is much more appropriate name for "Sea of Japan" with historical and universal facts and data.
Sea of Japan is a reminnder of the history between South Korea and Japan.
East sea is not Japan's territorial sea. In the old maps and old geography books of Korea and Japan, none of them shows the name, "Sea of Japan". However, "East Sea" is a name used since a long time ago between Koreans. The first record of "East Sea" was in The History of the Three Kingdoms.
In conclusion, the name "Sea of Japan" is an inappropriate name for the sea which doesn not has a owner. And I can support the name "East Sea" was used more with Korea and Japan's historical maps, and the name "Sea of Japan" is a method of Japanese imperialism. So I wish you can change the name "Sea of Japan" to "East Sea" or at least with the simultaneous use of both names; ¡°East Sea/Sea of Japan".