Search for a Friend on the Veldt

Once you have the Airship, you can go to the Veldt to search for one of your friends.

Prepare and Go to the Veldt

Go to the Airship and form a party of three people. Then land on the northeast continent on the map to find the Veldt. Fight battles until Gau appears. Just wait for a while, and Gau will join you. He can learn more Rages on the Veldt just like he did before.