The name Donghae, literally East Sea, has been used in Korea for over 2,000 years, including in History of the Three Kingdoms (1145), the monument of King Gwanggaeto, and "Map of Eight Provinces of Korea" (1530). The first documented map to name the area the Sea of Japan was the world map drawn by the Italian missionary Matteo Ricci in China (1602) named Kunyu Wanguo Quantu. No Japanese record published up to the late-18th century indicated any name for the body of water. Furthermore, South Korea has pointed out that a few 19th-century Japanese maps referred to the sea as Chōsenkai, literally Sea of Joseon, including the "Simplified Map of Japan's Periphery" (1809) and "New World Map" (1844). South Korea argues there was no standard name prior to Japan's military expansion in the region in the late 19th and early 20th centuries. Additionally, it specifically states that the name Sea of Japan was not widely used, even in Japan, as late as the mid 19th century. Thus, South Korea argues that the current name reflects active promotion by Japan during a time when Korea could not represent its interests internationally.

South Korea argues that historically the more common name was East Sea, Sea of Korea, or another similar variant. South Korea further argues that the name Sea of Japan did not become common until Korea was under Japanese rule, at which time it had no ability to influence international affairs. Japan argues that the name Sea of Japan has been the most common international name since at least the beginning of the 19th century, long before its annexation of Korea.