The Republic of Korea has been used as the name East Sea since 59 B.C. Even on foreign maps, the name of the East Sea is mostly recorded as 'Sea of Korea' until the 18th century. However, in the 18th century, Asia began to be introduced in Europe around Japan, and it began to be listed as 'Sea of Japan'. The designation of Sea of Japan goes against the UN's naming principle that "the maritime designation adjacent to the two countries cannot use the national name of either country." Therefore, the sole indication of 'Sea of Japan' is an error and at least simultaneous indication with 'East Sea' is desired.