MapleStory DS/Mage

When you start as the Mage, just follow along the story prologue. When you reach an event where the teleporter area thingy disappears, keep going along. In chapter one, go to the Thief's place. In other words, go to the remaining teleporting portal (if I remember correctly, it should be at the bottom-left/right screen). Keep going along until you reach a certain point that starts a cutscene (or event, to be precise). The Thief should come and talk to you, and when you finish, keep heading along to the left/right (towards the teleporting portal that you DIDN'T come from).