A broken ship becomes a disagreement about who the crew can afford to lose.
Water Seven seems built to solve the crew’s problems: a city of shipwrights where Skypiea’s gold can purchase repairs and perhaps a new specialist. Instead, the inspection reveals damage the Merry cannot recover from. For Luffy, accepting the diagnosis is a captain’s responsibility. For Usopp, already ashamed after being beaten and robbed, abandoning the ship sounds like a rule under which damaged crewmates might eventually be discarded too.
Robin’s disappearance turns that internal fracture into an external crisis. An attack on Mayor Iceburg implicates the Straw Hats, while the city’s trusted workers conceal a Government intelligence operation. The incoming Aqua Laguna creates a deadline independent of anyone’s motives. Emotional decisions, political violence, and geography all converge on the last train leaving the city.
Story
The cost of an honest diagnosis Ch. 322–331
A frog swimming the sea-train tracks and a grandmother named Kokoro at Shift Station point the crew toward Water Seven, a city built in tiers on a rising sea where the streets are canals and the shipyard is the state. Galley-La’s foremen agree to look at the Merry, and a shipwright named Kaku runs the length of the hull and comes back with a verdict: the keel is broken, and a ship with a broken keel cannot be repaired, only replaced.
The same afternoon, Usopp is robbed of most of Skypiea’s gold by the Franky Family and beaten into the pavement when he goes to the Franky House to demand it back. Luffy, Zoro, Sanji, and Chopper flatten the house in reply, but the money is spent and Usopp’s ribs do not heal with the building. He returns to the inn to hear his captain say that the crew will buy a new ship.
The fight that follows is not about wood. Usopp hears that a damaged thing which can no longer keep up will be left behind, and he is the one who was just beaten and robbed. He tells Luffy he is leaving the crew and challenges him for the Merry. Luffy, who has never lost a crewmate, accepts because he does not know how else to answer.
A duel between friends Ch. 332–333
They fight on the shipyard at night with the Merry between them. Usopp has prepared everything: smoke, oil, flame, an Impact Dial charged with his own body, and a precise knowledge of where his captain will be standing. He hits Luffy harder than most enemies have, and Luffy, who cannot bring himself to dodge, takes it.
It ends the only way it could. Luffy lands one blow and stands over a friend who cannot rise and will not stop talking. He leaves the ship to Usopp and walks away with the rest of the crew, and the Merry stays where it lies with the sniper who chose it over them.
The city turns on its guests Ch. 334–341
Morning brings a headline: Mayor Iceburg has been shot in the night, and the assassins wore masks and travelled with a tall woman who could grow arms out of a wall. Chopper and Sanji saw Robin walking with a masked man hours earlier and were told to forget her. The Galley-La shipwrights, who worship Iceburg, come for the Straw Hats with tools in hand, and the city closes its canals to them.
Franky returns from a trip to find his house in splinters and hunts down the man responsible. He and Luffy fight through the streets until Franky’s Coup de Vent sends the captain flying and the pursuit scatters both of them. Meanwhile the sky turns yellow. Aqua Laguna, the yearly tide that swallows the lower city, is coming in a day.
Robin meets Sanji and Chopper in an alley long enough to say goodbye. She tells them they will never see her again and gives no reason. The crew that arrived to buy a ship has now lost its sniper, its ship, and its archaeologist, and is wanted for attempted murder.
The city’s familiar faces change Ch. 342–347
Luffy, Zoro, Nami, and Chopper break into Galley-La headquarters that night to find Robin and clear their names. Robin is there, and so is Paulie, and so are the masked assassins, who remove their masks one by one: Rob Lucci, who has never spoken above a pigeon’s ventriloquism; Kaku, who checked the Merry’s keel; Kalifa, Iceburg’s secretary; and Blueno, the barman. They are CP9, Government agents who have lived in the city for five years to find the blueprints of an ancient weapon.
Iceburg, wounded but awake, tells them the rest. The blueprints for Pluton are not with him; he passed them to Franky years ago. Robin is helping the agents because of a bargain: if she surrenders herself, the Government will not turn the Buster Call that erased Ohara on the Straw Hats. She tells Luffy to leave and never look for her.
Lucci settles the argument. He throws the Straw Hats through the walls of the mansion with a strength none of them has faced since Aokiji, and Robin walks out with the agents while the building burns behind her. Luffy lands wedged between two buildings, unable to move, with the tide coming.
Franky’s secret in the water Ch. 348–352
Franky retreats to the Franky Family hideout beneath the bridge, where his followers have been hiding Usopp, and where Franky keeps a stack of drawings he has never let anyone see. CP9 finds him there. He fights Lucci and Kaku with everything his cyborg body holds, and loses. The agents take Franky and Usopp both, for the blueprints in his head and the Merry’s sniper who happened to be present.
Nami finds Iceburg long enough to learn the whole of Robin’s reason, then runs through a city that is evacuating upward. Aqua Laguna is higher than anyone alive has seen, and the lower districts are already under it. Chopper and Nami find Luffy jammed between two walls and Zoro stuck in a chimney, and neither can be pulled free by hand.
Sanji, meanwhile, has gone to the sea train. He watches Robin, Franky, and Usopp loaded aboard the Puffing Tom and steps onto it as it pulls out of Blue Station, alone.
The shipwright who built for the wrong king Ch. 353–357
Tom was a fish-man shipwright who built the Oro Jackson, the ship that carried Gol D. Roger to the end of the sea. For that he was condemned to death, and for that he asked the court for time: let him build a sea train that would save the sinking city, and judge him afterward. Iceburg and a scrap-loving boy named Cutty Flam were his apprentices, and the Puffing Tom rose out of Water Seven over ten years.
Cutty Flam built warships from junk in his spare time, and a Government agent named Spandam stole them to attack a judicial ship so that the blame would fall on Tom. Tom confessed to a crime he had not committed in order to protect the boys, and was taken away to Enies Lobby. Cutty Flam tried to stop the train that carried him and was crushed beneath it.
He rebuilt himself from wreckage on a scrap island, became Franky, and came home four years later to find Iceburg mayor and himself officially dead. Iceburg gave him one task: keep the Pluton blueprints that Tom had entrusted to them out of every hand that would use them, including the Government’s.
The rescue begins before the island ends Ch. 358–366
Nami reaches Luffy with the truth: Robin is not a traitor but a hostage who sold herself for them. Luffy tears himself out of the wall with the news. The crew that remains gathers at Shift Station where Kokoro unveils Rocketman, a prototype train with no brakes, and Paulie and the Galley-La foremen and the Franky Family climb aboard for reasons of their own.
Rocketman leaves the rails behind and rides the flood into the storm. Aqua Laguna rises across the track as a single wall of water; Zoro cuts a train-sized hole in it, and Rocketman goes through. Behind them, Water Seven disappears under the tide it has always survived. The crew that could not agree on a ship has a single direction again.
Cars uncoupled in the storm Ch. 367–374
On the Puffing Tom, Sanji works forward through the cars alone, cutting them loose one by one and fighting Wanze, the cook who fights with noodles, and a squad of Marines. Franky and Usopp, who has arrived in a mask and a cape as the hero Sogeking, join him. Between the three of them and the storm, they take the car where Robin is being held.
Robin refuses to be rescued. Sanji offers her his hand and she tells him, coldly, that she will not come, that she cannot come, and that they are killing her by trying. Blueno opens a door in the air and takes her through it before anyone can argue. The Puffing Tom pulls away toward the island where the sun never sets, with Robin aboard.
Rocketman catches up with the last cars in the rain. Zoro cuts Captain T-Bone out of the way on the roof, the crew hauls Sanji, Franky, and Sogeking aboard, and everyone left standing agrees on one thing: they are going to Enies Lobby, and there is no way back from it.