How to Get the Onion Knight in Final Fantasy 3

Send a letter to every available major non-playable character in the game. Access Mognet by speaking to a Moogle, located in every town. Mognet is a letter delivery system that can be used to send letters to NPCs and friends you have registered. The characters you must send a letter to are Topapa, Takka, Princess Sara, Cid, Four Old Men and Alus. Send a total of four letters to Topapa throughout the game.

Register a friend through Mognet and send him a total of seven letters through the system. Your friend must have a Nintendo DS and his own copy of "Final Fantasy III." Connect the two game systems with a USB cable or setup Wi-Fi on both systems. Visit a Moogle in any town and select the "Register Friend" option. Select the friend you with to register and press the "A" button. The friend will be added to your address book.

Send a letter to Topapa after you have completed. After sending him a letter, he will reply and tell you some children are in danger and to visit Ur.

Speak to Topapa in Ur. He will ask you to rescue the children. Head to the Altar Caves, located in the northern portion of the town.

Move your character south, within the cave, then travel down the stairs. Head west until a cutscene begins. You will see the four children surrounded by Bomb monsters. Defeat the three Bombs in battle to save the children. After you save the children, they will give you a shard of the Wind Crystal. This will allow you to change into the Onion Knight job.