Rescue the other two players and finish the game. If done correctly, the phrase "You've got the special key" will appear after the credits. Save the game. Start the game that was just saved. Enter the room with the large mirror on the second floor of the mansion. Unlock the door in the back. Enter the closet and move all the way to the end of the rack of clothes. Then, a message asking "There is an outfit that fits you perfectly, do you want to put it on?" will appear. Now select "Yes" to change your character's clothes.