New in softcover. Hardcover was published in 2022. This monograph discusses the dispute in geographical naming of the sea between Korea and Japan, which has been a long-lasting issue in East Asia and beyond. The book covers the modern history of the dispute, reveals the origin of the names for the sea between Korea and Japan, and the historical change of the name on ancient maps of Korea, Japan, and the West, and tracks the naming trends of the East Sea in geography textbooks in the pre-modern and modern times. The book also contains suggestions for some tangible solutions for the issue.