The plot I had in mind would be the assembly of a pirate crew where players would take up a role as one of the critical positions in the crew with characters of varied backgrounds. It would take place 90 years after the death of Gold Roger but in a slightly alternate timeline, so the existence of certain prominent people would be nonexistent and the events that occurred during the anime and manga were very different or didn't happen at all. Since the destruction of various renowned pirates of the past, the World Government expanded its control of the world and has a greater influence on the seas, namely the Grand Line.
Players would band together for a variety of reasons, all with the collective goal of breaking into the Grand Line and traversing the Gauntlet of Liberty, another name for the Grand Line in order to pursue the crew's dreams and one particular goal in particular that is revealed early in the RP when the crew is coming together.
I plan for it to be somewhat sandbox-ish, with the crew encountering various events that involve the crew's goals and obstacles that could prevent the crew from continuing their journey, but I do have a progression path in mind after the crew forms at the first setting.
If this interests anyone, let me know. The RP itself is almost complete and I should be posting it soon.
You had me at One Piece. Make, and I will most likely join. (If I have time. Which I guess I do.)