Suimui Utaki is said to be the origin of Shurijo Castle. There is a Ryukyuan legend surrounding this.
──From the world of the gods, Nirai Kanai, Amamikiyo was given orders to create an island and came down to this world. In order to create the island, Amamikiyo brought earth, stone, grass, and trees. Amamikiyo also created 7 forests which were the Utaki. The 7th and final Utaki was Suimui Utaki. In other words, with this final utaki, the island was complete.──
In reality, Suimui Utaki existed long before Shurijo Castle was ever built. Rather it is exactly because Suimui existed that they sought to contain the fortune and good luck of this utaki and chose to build Shurijo Castle here in the first place.
Behind the utaki lies Kyo-no-uchi. Suimui Utaki was actually one portion of this forest. However, once Shurijo Castle was built and became the center of the Ryukyu Kingdom, it became necessary to expand and develop the castle itself. However, to move or destroy Suimui Utaki was unthinkable.
This is why the utaki has remained as is to the present day.
Once the island was completed, Amamikiyo allowed one man and woman to live here. And thus, 3 boys and two girls were born and the eldest boy became the next king. The second son, the Aji. The next the Hyakusho. The eldest daughter would become the Kikoe-Ogimi. The youngest, Noro. Each would go on to become the founder of a line of lineage.
These were the foundations of the kingdom as well as the political system. With the king serving at the head of society, the aji were the leaders of each domain, and the hyakusho worked beneath them. The older sister would become the most revered goddess Kikoe-Ogimi and the youngest sister would be the noro which managed the prayers of each domain throughout the Kingdom.
This legend may have just been a necessity in order to create a state with complete unity of the church and state. This legend granted the king authority and a reason as to why the king was who he was. Just as the Japanese Emperor traced his roots back to Amaterasu and Ise Jingu, the Ryukyuan King traced his roots back to Amamikiyo and Sefa Utaki.
If you are interested in learning more about Sefa Utaki, make sure to check out our official guide.