Mii usage
Mii characters appear as playable and background characters in Pop'n Music. To play as a Mii, the player must fully clear a number of the game's songs. Since the game has a flat 2D art style, Miis are rendered as 2D icons placed onto several body sprites which differ based on stage selection. They are also sorted by alphabetical order on the character select screen.
Despite being flat 2D icons, Miis are expressive in this title. A Mii will cycle between their angry and sad expressions while sweating when failing a song, and will look happy while performing a song well.