Episode 521

"The Battle Begins! Show the Training Results!" is the 521st episode of One Piece.

Summary
The episode starts in Grove #17 where the Thousand Sunny and the Straw Hat crew (excluding Luffy, Zoro, and Sanji) is. Rayleigh gives Nami information about the weather in the New World. They are all expecting to see how Luffy has evolved in 2 years of training. The crew is afraid that Luffy might have caught up in some trouble. They want to inform Luffy, Zoro and Sanji that they must go to Grove #42 and set sail for the New World. Chopper has something on his mind in case they're caught in trouble.

Meanwhile, Brook gets away with the Rosy Life Riders, from the Sabaody Dome. The Marines are fighting the the fans of Brook because the fans don't want them to hurt Brook. Zoro and Sanji are fighting in front of people who are astonished by both Zoro's and Sanji's powers. Suddenly, Franky calls from the Transponder Snail to tell them that the Marines are on the way to find Luffy, Afterwards they hear an uproar coming from Grove #46

In Grove #46 where the pirates have gathered, Fake Luffy is about to show his new subordinates what he intends to do to Luffy but he's interrupted when the Marines arrives to arrest them all. Fake Luffy orders Caribou to use the Marine soldier he captured earlier as a shield in order to create a path, but Caribou doesn't listen to him and instead kills the Marines scout. In an instant, a fight breaks out between the pirates and the Marine, a Marine attempts to attack Caribou with a sword without success, meanwhile, discovering his possession of a Logia Devil Fruit which he uses to smother the Marine before shooting him.

Just when it seems like the battle will end in the Impostor Straw Hats favor (with the fake Luffy announcing that the one who kills the most Marines will become his right-hand man), 2 Pacifistas arrive along with Sentomaru. PX-5 identifies Luffy from a long distance. Lip Doughty attempts to attack PX-7 but he is defeated with a single blow. Terrified, the Fake Straw Hats run away, only for fake Luffy to collide right into Sentomaru. When all the pirates see him, they think he is going to fight and show them his power. Sentomaru is confused as to why the pirates are calling him "Big Boss" and "Straw Hat". Then fake Luffy starts bragging about "being" Luffy, proclaiming that he is the son of Dragon, the grandson of Garp, that he was in the War of the Best, and about having a 400,000,000 bounty on his head -- only to get cut off by Sentomaru who smashes him over the head with his iron axe whilst yelling that Luffy is not a piece of trash like him. Sentomaru asks PX-5 to identify who he really is, revealing him to be Demalo Black, a low-ranking pirate with a bounty of 26,000,000. Everyone is shocked to learn that he's an imposter while the rest of the Fake Straw Hats run off. Luffy, meanwhile, upon hearing about his doppelganger, decides to get out before getting caught.

PX-5 locates Luffy and is given an order by Sentomaru to attack him. Luffy avoids the Pacifista's attack, with his disguise falling off in the process. Everyone takes a good look at him and they all realize he is the actual Luffy, which shocks the Fake Straw Hats when they realize who they were threatening. PX-5 attempts to attack Luffy again, but Luffy avoids all of his attacks. Then, by using Haki and Gear Second he completely destroys PX-5 prior to running away.

While running away he comes across the actual Zoro and Sanji. Sentomaru orders PX-7 to attack them, only for them to simultaneously defeat him, shocking the recruits of the fake Straw Hats, making them realize they are indeed the real deal. Luffy,Zoro, and Sanji all start running together towards the Thousand Sunny. Luffy stops for a moment because he senses Rayleigh. Luffy thanks him for everything he has done for him in the past 2 years and yells that he is definitely going to become the Pirate King making Rayleigh looking at him and smiling.

Anime and Manga Differences

 * Caribou first revealed his Devil Fruit powers against a Marine soldier, not against Drip (Fake Sanji) as he did in the manga.
 * In the manga, PX-7 was using his palm lasers against Zoro and Sanji before getting destroyed, but in this episode, he was using his mouth laser.
 * Fake Luffy announces that the one who kills the most Marines would be his right hand man. This was not mentioned in the manga.
 * In the manga, PX-5 launched one laser beam from its hand at Luffy, while in the anime, it fired three laser beams from its mouth.
 * In the manga, Rayleigh is seen with tears in his eyes upon Luffy shouting at the end.
 * The anime shows Sanji spinning to activate his Diable Jambe, though in the manga he doesn't need to.
 * The anime does not show the flames produced from Sanji's Diable Jambe when he attacks the Pacifista as it does in the manga.
 * In the anime, Luffy punched PX-5 with his right hand, while in the manga, he uses his left one.