Korea have used the term of East sea more than 2000 years, not the sea of Japan. Also, a Korean island named Dokdo was not in the sea of Japan. But Japan took it from Korea when Japan repressed Korea by force of arms. At that moment, we couldn't speak out it was wrong. But now, we are trying to speak out totally it was wrong. Still, Japan ignore the fact that Japanese and Korean history state with a lot of public documents. They jus told, "We don't care the term of Dokdo".
Japan would take Dokdo as Takeshima by using the term of sea of Japan. And I think we have to consider this situation about the term of sea of Japan.