Complete the indicated task, then retrieve the item from the front desk to unlock the corresponding costume.

Extra Costume 1: Complete the game.
Extra Costume 2: Get Lost and Found 06 and 23
Extra Costume 3: Get Lost and Found 09 and 36
Extra Costume 4: Get Lost and Found 12 and 48
Extra Costume 5: Get Lost and Found 14 and 25
Extra Costume 6: Get Lost and Found 39 and 45
Extra Costume 7: Get all Lost and Found items