The Fairy King or Spirit King, real name Simba, is the king of the fairies. He is the one who bestows upon Toan the Atlamillia, sensing a kindness and bravery within him. The Fairy King is a nature spirit, and one of the few, if only, fairies seen in the series.
When Norune Village and the other towns across The West were destroyed by the Dark Genie, he managed to encase the people, buildings and landmarks within Atla, giant spheres which can be opened using Atlamillia. Unfortunately for Toan, while this meant the towns were not destroyed, they were scattered about the various dungeons. The Fairy King also casts a special spell on Toan and his allies' default weapons to keep them from disappearing when breaking.
The Fairy king serves as Toan's guide, awakening him after the destruction of Norune and giving him lessons within Divine Beast Cave and gives Toan a guide just in case he ever forgets a lesson. He later appears as a merchant selling items within Dark Heaven Castle, while offering to store items. He sells higher tier items, such as premium water, premium chicken, attachments, and gems. He's also the only character in game that sells gems, but only after you reach the castle in the clouds.
The Fairy King, as should be expected from someone bearing the title, is a kindly old man. He is evidently caring and compassionate, as seen by his saving of the towns in Atla and bestowing upon Toan the Atlamillia. He is also extremely helpful, going out of his way to aid Toan many times in his journey. The Fairy king is an old, short man clad in yellow and red robes and a hat. He wields a staff topped with a blue crystal and sports a gray beard.