Levitania, known as Terra Nimbus in America, is a region in Reveria. To reach Levitania, you need to reach chapter 6 of the story after Crankshaft makes some improvements to the airship. After the main story is complete, you can access Levitania anytime by talking to Larkin to the east of Port Puerto Marina. Also, after completing Chapter 6, you gain the ability to get dragon and bird pets (requires Origin Island expansion) by talking to the Pet Vendor in Central Levitania.