In Japan, sea of japan, but in South Korea, the east sea. The problem is closely connected and South Korea and Dokdo to sensitive about this thinking. Although it is not currently fully covered by international law, it is not right to use the word as one.
In conclusion, But, simply swap ¡®the east sea¡¯, and I will not force. Just they can be used with the ¡®sea of japan¡¯ and ¡®the east sea¡¯.