On the Okinawa Island, the largest of the island chain, the Kingdom of Shuri was established around the 15th century A.D. Its political ideology was characterized by a Sun ritual, and the king was worshiped as a child of the Sun. Women had a sacred role on these islands, and priestesses had the role of introducing sacred power from the Sun to the royal palace. In the religious thought of this kingdom, Kudaka-jima Island was the most sacred. This tiny island in the southeastern sea off the shore of Okinawa Island occupied an important position in royal rituals, including an enthronement ceremony of the highest priestesses who were close kin of the king. In the Urasoe Dynasty, predecessor of the Shuri Dynasty, it was possible to see the rising Sun of the December solstice behind the Kudaka-jima Island, and the ritual on the December solstice was probably performed for the re-birth of the king. During the proceeding Gusuku Period between the 13th and the 14th centuries, several castles were constructed there with gates that opened toward the June solstice. This custom was meant to introduce the strongest power of the Sun into the sacred place of the castle. On Kudaka-jima Island facing these castles, there is a folk belief in celebrating both June and December solstices. This paper traces the process in which a primary folk belief of the Sun had been transformed into a political ideology in which the king himself became the Sun, radiating the land and the people.