You will find that there is no Video Game without you as the main character (with the exception of weird abstract games like Pong or Tetris). Pokemon Mystery Dungeon Explorers of Sky is no exception. However, it it different from most games in the fact that what you are depends on your personality. However, this will only affect some of the advantages and disadvatages during gameplay. The story of the main character will always be nearly the same.
Warning: Spoiler AlertEdit
On a stormy night, in the land of Pokemon, you find yourself zonked out on a beach. The following evening, a Pokemon (soon to be your partner) finds you. You wake up with only a couple of memories:
1. Your name
2. Having previously been human
3. And the obvious previous knowledge of how to speak, how the world works, social skills, etc...
While you are talking to the somewhat suspicious Pokemon, two thugs (Zubat and Koffing) steal something from it. You team up to retrive it. You venture through Beach Cave to the 5th Floor (Beach Cave Pit) and defeat the two lowlife theives. After getting the item back, you and the Pokemon form an exploration team.