text: South Korea wants the name `` East Sea '' to be used , either instead of or in addition to `` Sea of Japan ; '' while North Korea prefers the name `` East Sea of Korea '' .
simplified: Since 1992 , South Korea demands the world to use the names `` East Sea '' or `` Sea of Korea '' instead of `` Sea of Japan '' . South Korea argues that this sea area has been called `` East Sea '' since early times .