Four worlds

From Miikipedia

The Mii universe is split into four parts as follows.

• The Mii Plaza - This is where Miis are born and may spend much of their time.
• The Mii Parade - This is the Mii 'heaven', where Miis go after proving themselves.
• The Miilennial Plains - The endless plains below Mii Plaza.
• Wuhu Island - Technically part of the Mushroom Kingdom, this is the Miis' only outpost on other worlds.