One Piece: Romance Dawn Story

Twenty two years ago, the legendary pirate, Gold Roger was executed. His final words told that his treasure known as "One Piece" was hidden somewhere on the Grand Line. This started the Age of Pirates. Now, twenty two years later, seventeen year old Monkey D. Luffy desires to find One Piece, and become the Pirate King. But to do this, he needs a crew. <em class=de-emphasized>(from manga)</em>

Synopsis from Anime News Network