Mognet ( Final Fantasy III ) Mognet is a feature which first appeared in the Nintendo DS remake of " Final Fantasy III " . Unlike Mognet in " Final Fantasy IX " , this service is not for moogles , but for the player . Before the shutdown of the Nintendo Wi - Fi Connection service for Nintendo DS on May 20 2014 , people had the possibility to trade friend codes and send letters via the Wi - Fi network . Unfortunately , this means that current DS players can no longer utilize the Mognet service to its fullest , and new players will only be able to use local DS - to - DS wireless communication to access the extra features it unlocks . The player can send letters to many " Final Fantasy III " denizens , such as Princess Sara or Cid . It is through Mognet that the player can unlock the bonus dungeon and the secret Job class . Mognet works a little bit differently for the iOS , PSP and PC versions , the letters unlock at certain points over the course of the story . The player will have to read the new piece of mail at a moogle found in towns before getting the next mail . Using Mognet . Players use Mognet by speaking to moogles found in nearly every town in the game . In the Nintendo DS version , players may exchange letters with each other through wireless communication . This can be done remotely with two handhelds next to each other , or through Nintendo WiFi Connection by exchanging friend codes . Up to 28 friend codes may be stored at a time in the address book . Letters may be up to 125 characters long using no more than five lines ( 25 characters per line ) . In - game letters . Below is a list of all the letters players can receive from non - player character s . The ability to send mail to each character is unlocked at different points in the story . Whenever a player sends a letter they will instantly receive one back , which often reveals details of the NPCs ' lives after they met the Warriors of the Light , or offer commentary on the plot . Letters may only be sent once per hour . To receive letters after the first one in the Nintendo DS version , the player must send seven total letters to other players through WiFi . These can either be sent to multiple players or all to the same person . Since the iOS release lacks the ability to send mail to other players , these letters are unlocked automatically after the player has obtained the Fire Crystal from the Molten Cave , though some require a specific character to be at the lead in the party to receive them . Topapa . Players can send mail to Topapa when Mognet first becomes available after defeating the Djinn in the Sealed Cave . In the iOS version , Luneth must be at the party leader to receive any letters after the first . After receiving the fourth letter , the player may begin the Onion Knight sidequest . Takka . Players can send mail to Takka any time after Refia rejoins the party on Cid ' s airship when departing for Canaan . In the iOS version , Refia must be at the party leader to receive any letters after the first . To receive his fifth letter in any version , the player must have first reached Eureka . Receiving all five letters is a requirement for the Ultima Weapon sidequest . Sara . Players can send mail to Sara Altney any time after returning to Sasune after defeating the Djinn in the Sealed Cave . In the iOS version , Ingus must be at the party leader to receive any letters after the first , and in both versions he must be at the front to receive the fourth . Receiving all four letters is a requirement for the Ultima Weapon sidequest . Cid . Players can send mail to Cid Haze any time after they have dropped him off at his home in Canaan . The fourth letter cannot be received until the player has met the Legendary Smith . Receiving all four letters is a requirement for the Ultima Weapon sidequest . Four Old Men . Players can send mail to the Four Old Men any time after they obtain the Levigrass Shoes from Delilah in the Amur sewers , defeat Bahamut , Leviathan , and Odin , and after all treasures in the Sunken Cave have been obtained . All four letters are required for the ? ? ? dungeon sidequest . Alus . Players can send mail to Alus Restor any time after defeating Garuda in Saronia . In the iOS version , Arc must be at the party leader to receive any letters after the first , and to receive his fourth letter , the player must first obtain a job ' s Master Item by reaching job level 99 on one character , and speaking with the Legendary Smith . All four letters are required for the ? ? ? dungeon sidequest . Sidequests . Players can unlock sidequests through Mognet after receiving a certain amount of letters from specific NPCs . The Onion Knight . The player must send and receive four letters from Topapa . After the fourth letter is obtained , the player must travel to Ur and speak with him , and then to the Altar Cave where they must save some children from three Bombs . After the battle , the player is rewarded with a crystal fragment which unlocks the Onion Knight job . The Ultima Weapon . The Ultima Weapon quest is divided into multiple parts . First , the player must send four letters to Princess Sara , where she asks for help in repairing her mother ' s pendant . The player must send and receive five letters from Takka and once the fifth letter is obtained , he will tell the player about the Legendary Smith who can be found in northwest Saronia . When the player sends and receives four letters from Cid , they will be tasked with slaying a monster in his basement , and are rewarded with a piece of Orichalcum . By finding the Legendary Smith in Falgabard after opening the door to Eureka and giving her the Orichalcum , she will forge the Ultima Weapon from it . ? ? ? Dungeon . The game ' s bonus dungeon can be unlocked after completing both the Onion Knight and Ultima Weapon sidequests and receiving all four letters from Alus and the Four Old Men .