Fish-Man Island Arc

The Fishman Island arc is the twenty-fifth story arc in the series, and the second in the New World Saga of the One Piece series, continuing on from the Return to Sabaody Arc. The Straw Hat finally head for Fishman Island after their two years hiatus. But many surprises await them as they head for the undersea destination.

After the Departure: Last Thoughts from Sabaody Once More.
After the Straw Hats escape, the scene changes to a section Sabaody known as "No Man's Land". Coribou and Caribou along with their crew have captured the Impostor Straw Hat Pirates and are digging their graves. The fakes plead with the brothers to let them go. But they refuse, revealing that they had planned to kill the real Straw Hats from the inside after joining them and were not amused when they found out they were lied to. When Fake Sanji continues to plea, Caribou reveals he is a Devil Fruit user, turning his arm into a gooey substance and smothering fake Sanji's face. The Fake Sogeking tries to shoot him, but the cannon ball ends up absorbed into his body, revealing that it is a Logia-type. Caribou orders his men to bury the fakes while he excitedly said he managed to confirm the real Straw Hats.

Back in Grove 46, Sentoumaru reports back to his base, mentioning he captured Demalo Black and most of the pirates though the Caribou Brothers and the fakes (except Cocoa and fake Chopper) somehow disappeared from the plaza. He also comments on the Straw Hats' new strength and tells the base to call Marine HQ in the New World and warn them that the Straw Hats have revived.

The scene then moves to a shore where Rayleigh is watching the ocean. Shakky joins him commenting on how quickly the Straw Hats left. She then asks if Rayleigh is recalling something. He jokingly comments "maybe" then remembers when he first met Roger who surprisingly looked very much like Luffy when he was younger, even wearing a straw hat. Rayleigh then comments to Shakky that destiny is slowly taking shape and that Luffy has proven himself that he is worhty of wearing that certain Straw Hat. He also mentions that it wouldn't be a bad idea to live longer.

Undersea Adventure: The Route to Fishman Island
Meanwhile underwater, the Straw Hats marvel at site of the undersea world, one of which is the roots underneath Sabaody as well as the huge fish swmming around. Luffy and Zoro try to catch them, earning them bumps on the head from Usopp and Chopper for nearly bursting holes in the coating bubble. Sanji asks Nami to explain more about the coating, but seeing her simply move once again gives him a nosebleed that propels him out of the bubble. He managed to pass through the bubble without bursting it but winds up in the ocean. Luffy manages to reach through and grab him but is weakened once his arm is in the water. He manages to pull Sanji back in. The others comment on how much more weak Sanji becomes when he is around women now and worries about what will happen when they reach Fishman Island.

Robin then notices that ship's bubble shares the shame characteristics as those on Sabaody. Nami confirms it, mentioning that anything strong enough to pass through the bubble will just go right through it, allowing them to fire the ships weapons if necessary. When Usopp asks what could break it, Nami answers that poking multiple holes in the bubble will indeed pop it, so they have to be careful not to let a Sea King bite into it or smash into a reef. Luffy and Zoro once more try to go fishing, forcing Usopp and Chopper to stop them again.

Luffy remembers Hancock had fixed him food, so he brings it out for the crew while Usopp wonders why Hacchan isn't guiding them like he promised two years ago. Franky, after confirming that the ship is stabilized with Nami, says he needed tell the crew something. In the two years they were gone, both Hachi and Duval protected the ship the best way they could but both were heavily wounded and Hacchan had to retire and head back to Fishman Island. A year after he left, the marines found out about Sunny and came to capture it. However there was one more warrior who protected the ship: Bartholomew Kuma.

The Truth Comes Out: Kuma's Selfless Action
Franky explains that after he arrived back on Sabaody he had found Kuma heavily damaged and rusted. Kuma then declared his mission was complete and headed off much to Franky's confusion. Franky then found out from Rayleigh that during their battle against Kizaru, Kuma had whispered to Rayleigh that he was a Revolutionary and wished to help the Straw Hats escape. After blasting the Straw Hats away, he later met with Rayleigh and told him he didn't have much time left. Since he was treated like a guinea pig with the Marines, his body was becoming more machine then human. He then made a deal with Vegapunk that before his personality was completely gone to have a program embedded in him to return to the Straw Hats's ship and guard it until one of the Straw Hats returned.

The Straw Hats are astonished that Kuma would go to such great lengths to protect them, figuring that Kuma did it as a favor to Dragon. Franky then warns them that while they are indebted to Kuma for saving them, the next time they meet he will have likely become a heartless human weapon. With that said, the group decides to eat the lunchboxes Hancock made for Luffy (once again earning Sanji's anger after he woke up and learned the truth). They are unaware that the Caribou Pirates are right behind them, and Caribou is still obsessed with destroying them.