One of the countries visited in Tsubasa RESERVoir CHRoNiCLE, Koryo Country (高麗国, Koryo-koku) is a country separated into various regions, each controlled by a Ryanban. The town is a medieval feud much like ancient Korea, in which the governor or Ryanban rules over the place, even though there is a control over the governors from the central capital. Such is done by the so-called Amen-osa (Miteshu in the anime), who are warriors in disguise who observe that these Ryanban do not excede in their power, and if that is the case, they have the power to put him out of the position. The castle is surrounded by a magical barrier created by the Hijutsu (magic) of the Ryanban, this is why no one can rebel against him.