I have found some different information in your website. In your website, the name of the sea between Korea and Japan is described as "Japanische Meer". It seems unreasonable to use the name "Japanische Meer" which is decided in the period of imperialism because its original name is "East Sea" which has been used throughout history. Therefore, I believe that the body of water between Korea and Japan should be described as the “East Sea” or at least with the simultaneous use of both names; “East Sea/Japanische Meer.”