Contemporary Nation (Beyond the Earth by Nekomata Master) - Complete the 'Yima pose matching' mini-game 100%
Fresh (Chase! Chase! Chase! by Parquets) - Complete all the stages in the bicycle mini-game
Unlock EX Stage
Under Arcade - Challenge Mode, you have to aquire 110 or more points to unlock EXTRA STAGE, whatever EX Stage you play on the EXTRA STAGE is automatically unlocked, even if you fail the song.
Unlock Knock Out Regrets
The following pushbutton codes will temporarily unlock said songs for one arcade mode / free mode session when entered on the title screen. The numbers correspond to the Pop'n controller's buttons from left to right.
Knock Out Regrets (Punkish Girl) is permanently unlocked if you start the game with a DDR Str!ke save on your memory card.
Jet World (Hard Country), and Cassandra (Ska) are permanently unlocked if you start the game with a Guitar Freaks / Drummania V save on your memory card.
Code - Effect
38271619 - Unlock Jet World (Hard Country), and Cassandra (Ska)
97976868 - Unlock Knock out Regrets (Punkish Girl)