In which world does Sora first meet Merlin in Kingdom Hearts?

Sora first meets Merlin in Traverse Town in Kingdom Hearts. The encounter takes place in an abandoned house in the Third District, where the wizard has established a makeshift study.

Sora, Donald, and Goofy reach Merlin after Cid asks them to deliver an old book. Merlin then reveals that King Mickey requested his help and begins teaching Sora how to use magic. The meeting also introduces Fairy Godmother, who handles Sora's summon abilities.

Traverse Town is easy to confuse with Disney Castle or Hollow Bastion because Merlin appears in other locations across the series. In Kingdom Hearts II, for example, he lives in Hollow Bastion's restored town, while Disney Castle is Mickey's royal home. His first Kingdom Hearts appearance, however, is firmly tied to Traverse Town and its network of displaced survivors.