Successfully complete the game with the good ending and unlock Badtz-Maru's profile. Start a new game to have the option to play as Badtz-Maru.
Successfully complete a level with an "S" rank to unlock a bonus sailor costume.
Successfully complete all the cheerleader blocks in the Messy Park level to unlock the Cheerleader costume A.
Unlock Cheerleader costume A, then defeat all the cheerleaders again in the Messy Park level to unlock Cheerleader costume B.
Intentionally lose against the final countdown Boss to unlock the So Long! Round Earth! cinematic for purchase.
Defeat the final countdown Boss to unlock The Taste Of Victory cinematic for purchase.
Set the system date to any day in November to get Hello Kitty birthday themed title and loading screens.