These unlock the option to recruit various characters throughout the game. These do not work fully until after the game tells you about Recruiting.

Unlockable	How to unlock
Adel	Give her a Sturdy Cloth, Hunk of Copper, and Thick Hide.
Claire	Give her a photo of the Lafrescia Stem.
Corinne	Play hide and seek with her, and win twice.
Doctor Dell	Have him heal the sick girl in Balance Valley.
Donny	Buy An Indestructible And A Dark Coin, Then Give These To Donny.
Fabio	Catch a fish 60 cm or bigger in the lake.
Ferdinand	Give Him A Roasted Chestnut.
Gerald	Level up the gun he gives you twice.
Gordon	Give him Holy Water.
Mayor Need	Enter the combo to the safe (which is 1221).
Milane	Level up the weapon she gives you twice.
Mina	Complete ten rounds of Spheda after talking to her.
Olivie	Wint 1st Place in Finny Frenzy.
Parn	Give him Gold Paint.
Pau	Give him a carrot.
Polly	Keep delivering the bread to the places directed.
Priest Bruno	Put out all of the candles in the church.
Rosa	Say "Let's go together." when talking to her.
Rufio	Give him a photo of the moon.
Sheriff Blinkhorn	Run to the boat and back in under 2 minutes after talking to him.
Stewart	Give him the money for the auction.