Episode 521

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

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

Meanwhile, Brook gets away with the Rosy Life Riders, in the Sabaody Dome, the Marines are fighting the people. Roronoa Zoro and Sanji are fighting in front of the eyes of the people. Suddenly, Franky calls from the Transponder Snail to tell them that the Navy is on its way to find Luffy. In the end of the call 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 when the Navy arrives to arrest the pirates. Caribou takes an order from Fake Luffy to use the Navy soldier he captured as a shield to get out of there. But Caribou doesn't listen to him, takes out his gun and kills the Navy scout. In an instant, a fight broke out between the pirates and the Navy, a Marine attacks Caribou with a sword but it was absorbed into him. He is revealed to have a devil fruit ability, which he uses to smother the Marine before shooting him.

Just when it seems like the battle will end in the Imposter Straw Hats favor (with the fake Luffy announcing that the one who kills the most Marines will become his right-hand man), unexpectedly PX-5 and PX-7 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 the fake Luffy "Big Boss". 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 for Sentomaru to cut him off mid-sentence by smashing 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 him, 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 doppleganger, 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 tries to attack Luffy again, but Luffy avoids all of his attacks. Then, by using Haki and Gear Second he completely destroys PX-5 before running away.

While running away he comes along 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. Luffy stops for a moment because he senses Rayleigh. After Luffy thanks him for everything, he shouts that he is definitely going to become the Pirate King; Rayleigh looks at him whilst 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.