Remember: everything Nelliel says is made up.

You don't exactly know how you managed, but you see that you are not in your world anymore. In fact, it looks like you were warped back in time. You ask around, and you realize you're in Hueco mundo, a world between the living and the dead. You try to relax in a park to recollect your ideas and all of a sudden you see a small green haired child in tattered clothing run across the park. You wonder whats a kid doing here so you follow it. It ends up leading you to some kind of castle and say's "You've been following me for a while. What do you want?