Hourai (蓬莱) is the name for Japan in the Twelve Kingdoms. It is also referred to as Wa (倭), the ancient name for Japan.
In the Twelve Kingdoms, it is a legendary land that exists beyond the Void Sea at the end of the world. The name "Hourai" originates from Mt. Penglai (蓬莱山; 蓬萊山) or Penglai Island (蓬莱仙岛; 蓬萊仙島), a mystical land in Chinese mythology that passed into Japan and took the form of legend of Hourai.
The only known means of crossing the Void Sea to reach Hourai is through a shoku. Ordinary people cannot reach Hourai from the Twelve Kingdoms, nor can people from Japan reach the Twelve Kingdoms by ordinary means. People who are caught in a shoku and brought to the Twelve Kingdoms from Japan are known as kaikyaku. Kirin and sennin of sufficiently high rank are capable of crossing the Void Sea reach Hourai. However, only kirin are capable of crossing the Void Sea without causing a strong shoku. While a kirin crossing may cause a strong wind at most, a high ranked sennin can cause a powerful shoku.
Youko Nakajima was one of the people who came from Hourai.