Nanatama: Chronicle of Dungeon Maker

Press Square in town to bring up the menu. Go to system then to password. Both are the very bottom option on the menu. The items will appear in the delivery BOX in your home. They won't be delivered until the next day from when you put the password in. It seems only one arrives per day so you must wait for the following day if you put in more then one password to get the next item.