Chapter 672 is titled "My Name Is Kin'emon!!".
"Zoro and Sanji Carry a Hare and a Tortoise on Their Backs and Race for Them" - A request by P.N. Megane-Danuki (メガネダヌキ) in Akita Prefecture.
In the research facility, Law is confronted by the mysterious man, Vergo. Law desperately attempts to fight him, but is instantly defeated. Outside the facility, Caesar Clown has incapacitated Robin, Franky, Smoker, and Tashigi without touching any of them.
At the lake, Sanji saves the samurai's torso from being eaten by a shark, and successfully escapes from the lake before the surface is completely covered by poison. The reconstructed samurai introduces himself as Kin'emon of Foxfire, and destroys the Slime around them with his Foxfire sword style.
The chapter starts with the introduction of a man named Vergo. He asks Law if he thought they really knew nothing, saying they sent Monet in as a spy due to his boss' distrust of Caesar Clown. He muses on the fact that Law is a Shichibukai. Law asks him when he arrived, and he answers just moments ago. He explains he was in Dressrosa when he heard that an SAD tanker was heading out so he got on board, noting that it was the right choice. Law does not believe that Vergo's arrival was that coincidental and asks what he did to harm him. Vergo replies that if Law had done any harm, he would be dead right now, saying that Law cannot hide anything from adults. Law then says he will have to get rid of him, grabbing his sword. But before he can even begin to draw it, he suddenly drops it due to Vergo's paralyzing ability. Vergo then remembers he wanted to restate what he said earlier. He takes out a bamboo staff, darkening it by imbuing it with haki. He then brings it down on the back of Law's head, saying Law should call him Vergo-san from now on.
In front of the lab, the Marines are looking on in shock, as Caesar Clown has now defeated not only Luffy, but Robin, Franky, Smoker, and Tashigi, all without touching them. One soldier wonders if it was due to Haoshoku Haki, but another argues that the differences in their strength is not enough for it to work. Caesar's subordinates gloat about their victory in front of the Marines. Clown then orders for the five people he just defeated to be tied up, reminding them to use Seastone on the Devil Fruit users. He tells them to leave the Marines and enter the lab for shelter since weird things have started falling from the sky. He then observes that the Yeti Cool Brothers messed up, remarking that Law and the Straw Hats were a bit too much for them to handle.
In the center of the island, Brook and Zoro have to contend with the many blobs of slime that are slowly surrounding them. They have just learned that cutting them releases poisonous gas. Zoro suggests that since the things they are fighting are essentially jelly, Brook should eat them. Before they can argue further, Kin'emon screams out in pain. In the lake, Sanji has to contend with the freezing temperatures and the strain it is putting on Nami's body, repeatedly apologizing to her. He then notices the huge cloud of poisonous gas made by Slime. He realizes that his Kenbunshoku Haki is quite hazy, since any life energy he senses gets mixed in with that of the fish. He then looks up and sees a shark carrying the torso in its mouth.
Sanji immediately begins swimming after the shark. Back on the shore, Kin'emon is screaming in pain, even coughing up blood when suddenly he realizes he is not in pain anymore. Sanji is then seen kicking the shark with Joue Shoot. He then grabs the torso and begins swimming back up. The shark tries to bite him but is instantly killed by the poison in the water. Sanji then realizes he is surrounded. He wonders if he can make it with Nami's muscle strength, reluctant to put more stress on her body. He then uses Blue Walk to propel himself up and out of the now completely poisoned lake, much to everyone's relief. Kin'emon, now completely intact and getting his official introduction, cannot express how happy he is. Brook notes how tall he is. He asks Sanji his name, and Sanji asks why he is being so polite all of a sudden, considering he was verbally abusive only a little while ago. He says he is forever indebted to Sanji. Sanji tells him to man up and stop bowing. Brook interrupts, pointing out how the slime is slowly closing in on them.
Sanji was irritated that Brook and Zoro had not gotten rid of the problem yet. Kin'emon suggests they try burning it. He tells them that his blade can burn what it slashes. Kin'emon then proceeds to slash one of the slime blobs. As it burns, Sanji notices something strange only moments before the whole area is consumed in a blinding explosion. Miraculously, everyone survived the explosion completely untouched.
Brook asks Kin'emon what he did. Kin'emon remarks that even he was surprised, not expecting it to explode the way it did. He then tells them that he simply cut through the flames of the explosion, going on to say that his Foxfire Style not only cuts with flames, but also has a secret technique that lets him cut flames apart. He then declares that he will go to the lab to save his son now. Zoro, his curiosity about the samurai's fighting style awakened, offers to go with him to the lab to find his son.
- The tortoise and the hare having a race on Zoro and Sanji's backs are a reference to Aesop's fable "The Tortoise and the Hare".
- Vergo's name is revealed and he is fully seen for the first time. He subdues Trafalgar Law.
- This is the second time in the whole series that someone was introduced as "Mysterious Man", the first being Mr. 9 during the Laboon arc.
- Monet is revealed to be affiliated with Vergo and she was sent to Punk Hazard as a spy.
- Franky, Robin, Smoker, and Tashigi were all defeated by Caesar without him touching them.
- Sanji is officially confirmed to have Kenbunshoku Haki.
- Sanji uses Blue Walk in Nami's body.
- Kin'emon's body is finally back together and he properly introduces himself as Kin'emon, born in Kuri, which is located in Wano Country.
- Kin'emon says that he is indebted to Sanji.
- Kin'emon can cut with and through fire, thanks to his fighting style, which he names "Foxfire". With the help of this style, he defeated the Slime around them by igniting it and causing it to explode, then cut through the explosion as well.
- Zoro, interested in Kin'emon's fighting style, decides to help the samurai save his son.
- first introduction/new introduction
4: true affiliation revealed