Agartha (アガルタ, Agaruta) is a legendary world located in the Earth's core. It appears in Children Who Chase Lost Voices.
Background[]
According to Ryuji Morisaki's research, Agartha is an underworld. When the Quetzalcoatl realized that mankind had matured enough and their guardian role had ended, they retreated to this world, brought along some human clans, who became the Agarthans.
Topsider soldiers raiding Agartha in the past
According to the Amaurot village elder, Agartha later became a glorious kingdom, more than anywhere on the surface. However, because of countless wars waged by the Topsiders, humans from the surface, who came to plunder and kill, the cities were destroyed and the land was in ruin, with only a few villages left. To prevent further invasion, the Agarthans sealed off the entrances using the clavises.