Zephyr, now known as Z, rides the seas with only one goal: Destroy all pirates and their dreams at becoming King of Pirates. When Luffy and his crew encounter him at sea, not only are they utterly defeated by the man with an arm made of Seastone, Nami, Robin, and Chopper are turned 10 years younger due to Z's minion Ain. Luffy is so determined to win against him that he does not even notice Z's master plan that could sacrifice thousands of lives.
20 years after his escape from Impel Down, the legendary pirate Shiki, the Golden Lion, reappears causing massive upheaval to the Marines. During his long seclusion, he was able to come up with a scheme to bring the World Government to his knees. On his way to execute the plan, Shiki crosses paths with the Straw Hat Pirates and becomes so impressed with Nami's knowledge of meteorology that he abducts her to forcedly enlist her into his crew. Luffy and the gang end up on a strange land populated with monstrous beasts as they desperately search for Shiki and Nami.
Kōmei devises a plan where Zoro and Sanji take part in an eating contest, and the two eat a strange "good-for-nothing-only" mushroom that turns them into good-for-nothing men. The two are then locked in a jail cell. When the rest of the Straw Hat Pirates chase after their imprisoned crew, they land on the island of Nebulandia, which features a mysterious fog made from sea water, and it has the same effects as seastone. The Straw Hat Pirates' arrival on Nebulandia is also a part of Kōmei's plan.
The Straw Hat Pirates landed at Asuka Island, home of the most valuable sword in the world: The Seven Star Sword. Which was said to curse anyone who takes it in possession. When they got back to the Going Merry, they discovered that Zoro is missing from his guard duty. Before they could plan out a search party to relocate him. Luffy and friends escape from the port as Marines were on their tail. They found a new place to dock, which is near a village. Whose job is to keep the Seven Star Sword sealed. Soon it was attacked by the Marines, and among them is Zoro. Luffy and the others don't know why he's helping out the Marines. But it all comes to conclusion when Luffy encounters Saga: Zoro's childhood friend from Swordsman training.
Years ago, the fearsome pirate king Gol D. Roger was executed, leaving a huge pile of treasure and the famous "One Piece" behind. Whoever claims the "One Piece" will be named the new pirate king. Monkey D. Luffy, a boy who consumed one of the "Devil's Fruits", has it in his head that he'll follow in the footsteps of his idol, the pirate Shanks, and find the One Piece. It helps, of course, that his body has the properties of rubber and he's surrounded by a bevy of skilled fighters and thieves to help him along the way. Monkey D. Luffy brings a bunch of his crew followed by, Roronoa Zoro, Nami, Usopp, Sanji, Tony-Tony Chopper, Nico Robin, Franky, and Brook. They will do anything to get the One Piece and become King of the Pirates!