Unlock Dressing Room:
To unlock the dressing room you must have at least 10,000 Meseta in your character's inventory when starting. A new "Dressing Room" option will appear. The dressing room allows you to change your characters costume and hair-style.
Unlock New Difficulties Offline:
Beat Normal mode to open Hard mode
Beat Hard mode to open Very Hard mode
Beat Very Hard mode to open Ultimate mode
Unlock New Difficulties Online:
Get to level 20 to open Hard Mode
Get to level 40 to open Very Hard Mode
Get to level 80 to open Ultimate Mode