Sora walks out of the alley and in the town of Traverse Town...

Sora: This is totally weird... I'm, in another world!

Sora explores the town and then went to the Accessory Shop.

Cid: Hey there, how can I... Aw, it's only a kid.

Sora: I'm not a kid! And the name's Sora!

Cid: Okay, okay, simmer down. So why the long face, Sora? You lost or
somethin'?

Sora: No! Well, maybe. Where are we?

Cid: Huh?

Cid told Sora everything.

Sora: Traverse Town... So, gramps, is this really another world?

Cid: Don't call me gramps! The name's Cid! Anyway... Not sure what
you're talkin' about, but this sure ain't your island.

Sora: Hmm... Guess I'd better start looking for Riku and Kairi.

Cid: Well, good luck with whatever it is you're doing. If you ever run
into trouble, you come to me. I'll look out for you.

After Sora fully prepares himself by buying some equipment, Sora heads
to the Second District. In there, he saw a man who falls down on the
ground and dies. His heart came out and it formed into a Heartless.
Then, the Shadows appeared.

Sora: (wandering) It's those creatures from the island!

Sora fights the Heartless along the way while searching for the three
districts. After that, Sora goes back to the Accessory Shop and talks to
Cid.

Cid: Still haven't found 'em? Keep your chin up. Take another look
around town.

Sora goes outside. And then...

Leon: They'll come at you out of nowhere.

Sora: Who are you?

Leon: And they'll keep on coming at you, as long as you continue to
wield the Keyblade. But why? Why would it choose a kid like you?