Chapter 609 is titled "Adventure on Fishman Island".
Color spread: The Straw Hat Pirates, along with a giant raccoon king and a baby fox, are in a forest and fireflies are raining down on them. The caption on the top of the page says "Things are getting better and better!! A color page in commemoration of the charge into Fishman Island".
Luffy, Sanji, Usopp, and Chopper spend time in Mermaid Cove. Luffy learns important information about Jinbe. The Neptune princes show up looking for Luffy. Luffy punches Hammond and his crew with jet pistol. Sanji suffers a nosebleed so severe he may die from it.
The chapter begins with an infatuated Sanji playing in a pool with the mermaids in Mermaid Cove. The chef states his wish to live there, with a mermaid remarking how much fun he is. Luffy, soaking his feet on the side of the pool, comments on how nice it must be to swim. Keimi suggests that Luffy could wear a bubble, much to his surprise. Usopp asks if Sanji is just acting the way he is out of nature. Chopper states that he is glad Sanji is back to normal, going on to say that his blood stock is out of Sanji's blood type, S RH-, an exceedingly rare blood type. Luffy tells Keimi there is someone on the island he wants to meet. Keimi asks if it is the Mermaid Princess, Luffy says it is not, and that he wants to see Jinbe, explaining how Jinbe helped him cope with the loss of his brother, Ace. Usopp asks if Luffy is referring to the ex-Shichibukai, to which Luffy replies yes, calling him his friend, much to Usopp's disbelief. Luffy then remembers Jinbe saying he would wait at Fishman Island for Luffy to get there. Luffy tells Keimi about his promise to see him. Keimi remembers reading an article where Luffy and Jinbe were seen together. When Luffy asks where he is, Keimi replies that he is not on the island, going on to explain that after Jinbe abdicated his Shichibukai status, he could no longer stay on Fishman Island, so he and the Fishman Pirates had to leave. Luffy then asks if that meant he could not see him, and Keimi explains that the details of why he left are complicated, and that after the war, a lot of things changed on Fishman Island.
They are interrupted by the Medaka Mermaid Quintuplets, who came to tell them that a ship is coming. Nika, one of the quintuplets, tells Keimi it is a rare kingdom ship. Keimi realizes that the ship might be coming to arrest Luffy, and tells him that he must hide. Luffy, Usopp, and Chopper all hide behind rocks, while Sanji, still in the water, is shielded from view by a mermaid, trying to tell him to hold still while hugging his head to her chest, which the chef appeared to enjoy immensely. The ship, identified by Keimi as a royal gondola, essentially a large oarfish with some sort of carriage with oars sticking out built into it, approaches them. A nearby mermaid does not believe that there could actually be royalty aboard it, asking why they would come from Ryugu Palace to this little corner of the island. Trumpets then sound, heralding the arrival of the princes of Ryugu Kingdom, the Neptune brothers. One of them greets the mermaids, saying he has a queston for them. Three mermaids shriek with joy at the sight of the princes, asking them why they are there while Luffy, hidden behind a nearby rock, quietly looks on. He then wonders why there would be princes at Mermaid Cove, as do Usopp and Chopper. The Neptune princes, Fukaboshi, Ryuboshi, and Manboshi, then come forth. Fukaboshi explains that they received a report of illegal entry, asking if anyone had come by there. The mermaids reply that no one has come by. One asks if the people they are looking for really are important enough for the three princes to look for them in person. Fukaboshi then states that they have not confirmed if the illegal entrants are the people they are looking for.
From a distance, Hammond is watching these events take place. He is with a Fishman and a sea monster. The Fishman calls the princes the three strongest of the Neptune Army. Hammonds wonders why they are at the cove, saying it could be problematic. Fukaboshi then thanks the mermaids for their time, saying that he will continue searching elsewhere and that the border patrol must have made a mistake. He then apologizes to the mermaids for taking up their time, to which they reply that it was not any trouble at all. His brothers apologize as well. At this point, Sanji loses all self-control. The ability to contain himself became too much while his head was clutched against the mermaid's chest, and he erupts in his most massive nosebleed ever. The blood spurted extremely high, taking the shape of a mermaid doing a sexy pose. Chopper yells out in shock as he runs toward him. The mermaid holding him screams not knowing what just happened. The bottom half of Sanji's face is completely covered in blood and there is a lot more of it in the water. Luffy remarks that Sanji just lost a dangerous amount of blood. Usopp realizes that Sanji could not handle the excitement after all, and keeping it suppressed caused him to explode like this. Fukaboshi, checking some of the crew's wanted posters, realizes that the person he is seeing now must be Monkey D. Luffy. He then orders his Ammo Knights to advance. Hammond realizes that the Straw Hat Pirates are there now too. One crew member suggests capturing them while another argues that it would be bad if they got into a fight with the Neptune Army and that the princes are there too.
Chopper runs to Sanji's side, telling the guards to wait a moment while apologizing for entering illegally and asking the guards to postpone their arrest. He then asks for someone to donate blood, saying if not treated, Sanji would be dead in about thirty minutes. Chopper said Sanji's blood type is S RH-, an extremely rare blood type. He asks if anyone could donate and if fishman or merman blood could be transfused into a human's body. The guards stop in surprise. Luffy yells out, begging for someone to give Sanji blood. As some mermaids look on in fear, Chopper asks again if anyone has the necessary blood type. Usopp finishes the plea by saying that they cannot let Sanji die in such a stupid way. Keimi tells Chopper that humans, mermen, and Fishmen all share the same blood and it is transfusable. She is about to explain more but is interrupted by laughter. The laughter came from Hammond. He tells the Straw Hat Pirates that they must be out of their minds and that there is not a single creature on the island who would give blood to humans and if someone did they would get a "judgment in the dark" from someone who hates humans. Luffy then recognizes Hammond from their earlier encounter as Keimi suddenly dives under the water. One of the guards tells Fukaboshi that the person talking is Hammond from the Fishman District. Hammond tells Sanji to stay bleeding as he is and to die helplessly. He then tells about the rule put in place long ago, forbidding fishmen and humans from sharing blood. Usopp and Luffy look at him in disbelief. Hammond goes on to explain that the rule, ironic to the situation, was put in place by humans, fearing the fishmen as monsters, to prevent the mixing of bloodlines.
Fisher Tiger died as a result of this rule. During a bloody battle, he needed a transfusion badly. Humans prevented the transfusion from taking place and Fisher Tiger died as a result. Hammond then ordered them to abandon the life of one crew member and come with them to the Fishman District, as their boss, Hody Jones, wished to see them. Usopp then shouted that he did not know the detail of that law, and that if someone with S RH- blood came forth to help, he would thank them in any way possible. Hammond, ignoring Usopp, remarks that they will just have to take the Straw Hat Pirates by force.
He shoots a Utase Ami from a gun at them. Luffy sweeps the flying net out of the way, saying he would not listen to Hammond and that he had told him this earlier. He then proceeds to knock out Hammond and his accomplices with one Gomu Gomu no Jet Pistol each. Fukaboshi and some mermaids look on in shock while Ryuboshi begins to draw his sword. Hammond and the two other pirates have been knocked out cold. Someone then yells that Luffy forgot to deal with their sea monster. Luffy dispatches the monster by using Haoushoku Haki, intimidating it enough so that it would not fight, but not enough to faint. Chopper and Usopp were shocked at how the monster realized its own defeat without actually fighting.
Fukaboshi does not seem phased by this, saying he expected it, causing his brother to reply in disbelief. Keimi then reappears, having hijacked the royal gondola. She tells them they should go into town, as she saw a lot of humans at the port. Keimi then apologizes to the guards, promising to return the giant oarfish to them. Once everyone is on board, they set off, leaving everyone else, including the princes, at Mermaid Cove. On the gondola, Keimi apologizes, saying she would be willing to help if she were the right blood type for Sanji, but she is not. Usopp tells her she has nothing to be sorry for, as it all goes to back to Sanji having impure thoughts, pointing out the smirk on the chef's face as evidence. Chopper tells Sanji not to think of anything, as every second is precious.
Usopp then comments about the discrimination Keimi and Hatchan faced at Sabaody Archipelago two years ago, and how its roots run very deep. He follows up by saying he never thought that Sanji's perverted nosebleeds would lead to something this dire. Keimi changes the subject, saying she is worried about reaching town since she did not know if they would be able to find a compatible donor for Sanji. The reason for this is because no humans have visited Fishman Island in the past month except the Straw Hat Pirates. One of the Straw Hats asks why that is since the island is a famous spock. Keimi corrects him by saying it is a famous spot, but she does not know why there have not been any humans. She said there are rumors going throughout the kingdom that someone might be pulling the strings behind it.
Back at Mermaid Cove, Fukaboshi is talking to the Mermaids, saying them covering for the pirates created a huge problem, asking why they did it. The mermaids apologize, saying that the pirates were not bad people and friends of Keimi's and that they did not want the crew to get arrested for illegal entry. One mermaid says she hopes Sanji will be alright. Fukaboshi told the mermaids they were jumping to conclusions. Since the Straw Hat Pirates are already infamous pirates, it did not matter if they entered illegally since the army more or less knew who they were dealing with. Ryuboshi adds that they were looking for them for a different reason. Behind a surprised mermaid, Caribou's barrel can be seen, still sealed, with Caribou apparently listening intently. Fukaboshi states that they had just lost their chance to give the Straw Hats a message from Jinbe.
- Mermen are introduced, though one was seen with Hammond when the Straw Hat Pirates first reached Fishman Island.
- Members of Fishman Island's royal family are shown for the first time.
- According to Keimi, Jinbe and his crew left Fishman Island after Jinbe abdicated his Shichibukai position during the Whitebeard War.
- Sanji gets yet another nosebleed and this time, he suffers a critical blood loss.
- Sanji's blood type is revealed to be a rare type, "S RH-".
- Humans, merfolk, and fishmen are revealed to share the same kind of blood.
- According to Hammond, Fisher Tiger died due to lack of blood and humans refused to give him a transfusion.
- It is forbidden to cross blood between humans and merfolk and fishmen. This was a law made by humans long ago.
- The captain of the New Fishman Pirates is named Hody Jones.
- According to Keimi, humans have strangely not appeared on the island in months.
- The Neptune brothers of the royal family are revealed to be allies of Jinbe and Jinbe left a message for Luffy.
- first introduction
- first apparition