Water 7 Saga

CP9 Saga (ウォーターセブン編) is the fourth saga in One Piece. After the adventure in Skypiea, the crew lands safely back in the Blue Sea, only to find themselves confronting Foxy the Silver Fox in the Davy Back Fight, and soon after, Aokiji, one of the three Marine Admirals. Narrowly escaping Aokiji, the Straw Hat Pirates reach Water 7, a city of carpenters, where Luffy is on a quest to find a shipwright for the crew.

They soon fall into trouble though, making enemies with both the Franky Family: a ship dismantling group, and the Galley-La Company: a shipbuilding company which employs some of the top carpenters in the world. They also learn that the Going Merry is dying, and because of this, Luffy decides to get a new ship. Usopp disagrees with the decision and leaves the crew. Meanwhile, CP9 of the World Government captures Robin by her will and flees to Enies Lobby, while the crew attempts to get Robin back. Finally, they get her free and get a new crewmate: Franky, who is their shipwright. As they are leaving, Usopp apologizes and is welcomed back into the crew, and so the Straw Hat Pirates are ready to set sail with a brand new ship and shipwright, Thousand Sunny and Franky, along with Robin and Usopp back in the crew.

Story Arcs

 * Davy Back Fight Arc: 2004
 * Water 7 Arc: 2004-2005
 * Enies Lobby Arc: 2005-2006
 * Post-Enies Lobby Arc: 2006-2007