Birdpia (バードピア), also known as Birdopia, is the land inhabited by the birdman race located in the parallel dimension of Earth. The land was founded by an Ornithologist from the future who wished to live the rest of his life with his beloved birds. However, they're not there alone as the land was inhabited by a destructive beast named Phoenixia. Fearing that the beast might harms his friends, the Ornithologist along with some of his closest birds lured Phoenixia to the northern land before freezing it with ice and snow, trapping it for eternity.
Since then, the land became paradise for all the birdmen as well as the birds of all species from the normal dimension where they can migrate to. The land is connected to the real world through the special portals in the sky at random locations that can only be sensed by birds and birdmen. Most of the landscape is filled with greenery, trees and water springs. At the center is the tallest tree in Birdpia where the Ornithologist left his Time Machine behind on the treetop above the cloud.