The word of “WA” is often described in the Korean books. For example, it is said that the fourth king of Silla has come on a ship from “Tabana-koku”, which is “Tajima” in Japan. The Silla’s dynasty seemed to be connected with Japan. On the other hand, in Japan, it is handed down that Inahi-no-mikoto (son of the Emperor Jinmu) was a founder of Silla. It could be that the relationship of Silla and Japan is equal to two sides of the same coin.x Therefore, checking the example of word “Wa” in the Korean books (“Samguk Yusa” and “Samguk Sagi”) and “Karakuni” in the Japanese books (“Kojiki” and “Nihonshoki”), the Korean books have many motifs same as the Japanese books. Why have they the same motifs? It could be that there were exchange between Korea and Japan. Taking notice the resemblance of motifs and tracing the distribution of legends of “Utubo-ship”, there were the net-work of “Ama” (fisher) surrounding the East China Sea. It would be the world of ancient people.