FIrst, let me explain why Japan desires Dokdo for its territory. One of the biggest reasons is the resourses under Dokdo. Known as 'blazing ice', methane hydrate is buried under the sea near Dokdo. Since it releases less carbon dioxide than coal when burned, methane hydrate is taking the center stage of future eco-friendly resourse from all parts of the world.
But again, Dokdo has never been the territory of Japan and is clearly South Korea's territory. Numerous historical records support this fact. In Samguksagi - one of the oldest existing historical books - there is a record that An Yong-bok, who was the fisherman of Silla, conquered Usanguk. Also, the distance between the Oki island, the nearest island of Japan from Dokdo, is about 157 kilometers, which is approximately 68 kilometers farther than Korea's Ulleungdo. The Sejong chronicles, the official letter during Joseon dynasty, also mentions that the distance between Ulleungdo and Dokdo is close enough to see Dokdo from the other if the weather is fine. In 1900, Dokdo was officially incorporated into Gangwon-do province through the forty-first article of Korea's imperial order. Even some documents in Japan support that 'Dokdo' is the appropriate name and that the territory belongs to Korea.