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. This book is a useful resource for students and scholars in the fields of political geography, historical geography, cartography, diplomatic history, international relations, politics, and other related disciplines. It also appeals to international experts in hydrographic organizations and the United Nations, and geography and history teachers. The book is also interesting for the general readers interested in the topic of geographical naming disputes.