Chapter 670 is titled "Blizzard With a Chance of Slime".
Request: "Robin Interferes with Franky Arm-Wrestling a Gorilla" -Takahito Ogura (小倉孝仁) in Canada.
After arriving, Luffy is attacked by Tashigi and Smoker who were in each other's bodies (much to Luffy's amusement). Luffy evades their attacks and says he will fight Smoker when he is back in his own body. Franky manages to break down the lab entrance with his laser and calls Luffy and Robin to come. Suddenly, everyone on the battlefield sees a huge ball of slime land on the ship that the G-5 Marines stole. After being ignited by a Marine's flamethrower, it explodes violently, destroying the ship. Afterwards more huge slime balls begin raining from the sky on all sides and the people watching are overwhelmed by the toxic gas emitted from them. Caesar Clown then reveals himself on top of the destroyed ship, explaining his pet's ability to transfer itself from the other side of the island. Zoro, Brook, and Sanji see the Slime spitting pieces of itself across the distance. Caesar exclaims that once all the pieces are here, the whole area will turn into another poison gas incident. Luffy then manages to grab Caesar, much to his shock.
Surprised by the sudden appearance of, Robin, Franky and Luffy, the subordinates of Caesar Clown struggle to organize a counter-attack. With Franky blowing a group of them away with his Strong Right, Robin and Luffy discuss where they'll find Caesar as it would be unlikely for him to be outside. Tashigi (in Smoker's body) approaches Luffy demanding to know what he is plotting on the island, while the latter (ignorant of the body-swap) expresses relief that 'Smoker' is okay. Frustrated over being ignored, Tashigi goes to attack Luffy, finally managing to make a conscious transformation with Smoker's Logia ability. However, Luffy is easily able to dodge and subdue her, questioning how 'Smoker' had become so weak after the time-skip.
Seeing this, Smoker (in Tashigi's body) quickly moves in to strike Luffy, hitting him with a barrage of attacks using his seastone-tipped jutte. Confused, Luffy does not understand how 'Smoker' became so weak, while his second-in-command (whom Luffy has forgotten the name of) has become so powerful. Declaring himself as the real Smoker, the Marine again lunges towards Luffy who narrowly dodges the blow, stunned at this claim. Robin then interjects, explaining the possibility of Law having something to do with the change which helps Luffy understand, who then breaks into laughter once realizing the situation.
Not impressed by the pirate captain's attitude, Smoker attacks out of anger which Luffy manages to dodge again, entering Gear Second and quickly moves in front of Smoker, claiming that he will postpone their fight until the Marine is in his original body and at full strength. Suddenly everyone is surprised after a large explosion is set off, and it is revealed Franky had already made it to the front entrance and blown the door open with his Franky Radical Beam. Calling for the others to follow him inside, they are then interrupted as a strange blob-like substance begins to rain from the sky.
Landing onto the ship the G-5 Marines had commandeered, it quickly reveals itself to be hostile, and very dangerous. Beginning to emit poisonous gas after being attack, the Marines quickly equip themselves with gas masks and try to remove the threat from their ship. With the blobs beginning to merge and grow, one man tries to push it away only to suffer acidic burns. Claiming it looks weak to fire, another Marine pulls out a flame-thrower and begins to burn the unknown mass, which initially starts to whither away. Thinking they were successful, their victory is short lived as an enormous explosion engulfs the boat and surrounding water, distracting everyone on the shoreline as the boat is reduced to splinters.
Smoker and Tashigi can only look on as their men are decimated, while Caesar's subordinates laugh it off, claiming the menace is finally gone. Contrary to their belief, more of the poisonous blobs begin to rain from the sky, and Caesar Clown himself is revealed to be watching the disaster unfold. Claiming the monster does not like water, the blobs they see now are in fact parts of a much larger body isolated on the fire-side of Punk Hazard, which is firing itself across the lake one piece at a time (Sanji (in Nami's body), Zoro and Brook watching the process in the meantime).
Damning everyone present once his monster finally arrives, Caesar is interrupted mid-sentence by Luffy whose one-track mind has him focused solely on capturing the man.
- The cover shows Franky with a new hairstyle.
- Luffy fights Smoker and Tashigi while they are still stuck in each other's bodies.
- Luffy is shown being able to grab Smoker's body without being subjected to his normal intangibility for the first time, due to Haki usage.
- Luffy tells Smoker that they will have their fight when Smoker returns to his own body.
- More of Slime's properties and abilities are explained:
- As stated by Caesar Clown, it is not good with water, so it shoots itself across the water to reach the other side of Punk Hazard.
- Attacking or coming into contact with it releases poisonous gas.
- Igniting it causes it to explode violently with even small quantities being enough to destroy a large ship.
- "Smoker" (Tashigi) is seen crying for the first time.
- Caesar appears before the G-5 Marines and the Straw Hat Pirates.
- Luffy grabs Caesar, starting their confrontation.