I found an error marking East sea as Sea of Japan. East sea has been Koreas territory since the 6th century, when Dokdo was found. Dokdo-an island locating in the middle of East sea- is belonged to Koreas jurisdiction as well as the East sea. Korean armies are dispatched and they take care of the island every single night and day.
However Japan is continuously asserting that Dokdo is part of Japan, providing old documents as evidence. This cannot be a true basis that proves Japans claim since Japan damaged tons of Koreas historical materials over the 35 years they forcibly ruled Korea. They are just arguing with hardly acceptable evidences.