A mule is a character created solely for the purpose if harbouring items in their inventory. Due to limited inventory space, the wide selection of items in Maple Story (paricularly "et cetera" items) as well as the very small number of items the bank NPC can carry without purchase from the Cash Shop), many players prefer to use extra characters ("mules") to carry their items. There are several methods for item transfer:
- Character to Character - if the player has multiple computers, characters from another account can meet the player's main character and "trade" items.
- Bank transfer - The NPC's bank operates via accounts. This means that another character from the same account as the player's main character can simply walk up to the bank NPC and withdraw items placed there by other characters from the same account.
- Mail delivery - For the cost of 5,000 Mesos, a player can send items in a mail package to another player.