Volume 68

Volume 68 is titled "Pirate Alliance".

Cover
The colored cover is bluish-white, and so is the title logo. A unique feature is that the top of the title logo is covered in snow. The author's name is written in red and orange.

Caesar Clown surrounds the center of the cover, with his torso and face in the top right. Surrounded by him are portraits of, from right to left, Smoker, Luffy, and Law. On top of those portraits are the same three characters, shown from a top-down perspective. Smoker and Luffy stand next to each other, with Law behind Smoker. Snow is falling in the foreground.

Chapters

 * 668. Pirate Alliance (海賊同盟): Luffy accepts Law's proposal, and Law returns Franky and Chopper to their original bodies. The Straw Hats and Law set their objectives, while some centaurs release a slime creature.
 * 669. The Operation Begins (作戦開始): Zoro, Sanji, and Brook recover while the samurai is rendered immobile due to his torso being submerged in water. Caesar reveals the slime was created from the incident four years ago, while the Straw Hat Pirates and the Marines attempt to break into his base.
 * 670. Blizzard With a Chance of Slime (吹雪ときどき): Luffy battles Tashigi and Smoker as the invasion begins, but balls of slime begin to rain down and split themselves. Caesar then reveals himself, but Luffy manages to grab him, to his shock.
 * 671. Gasu Gasu no Mi (ガスガスの実): Sanji dives into a slime-infested lake to look for the samurai's torso. Luffy battles Caesar, who reveals that he can become and control gas. Luffy has the upper hand at first, but he suddenly collapses. Meanwhile, Law is confronted by a mysterious man.
 * 672. My Name is Kin'emon!! (拙者!! 名を錦えもんと申す!!): The mysterious man, Vergo, easily defeats Law as Caesar easily defeats Robin, Franky, Smoker, and Tashigi. Sanji retrieves the samurai's torso and puts him back together. The samurai then introuduces himself as Kin'emon.
 * 673. Vergo and Joker (ヴェルゴとジョーカー): Nami and Usopp struggle to keep the children under control when Caesar suddenly appears. Zoro, Sanji, Brook, and Kin'emon flee from the axolotl-shaped slime. Vergo takes Law, Luffy, Robin, Franky, Smoker, and Tashigi captive and prepares to kill them, with Law revealing Joker is Doflamingo's Underworld alias.
 * 674. Spectators (傍観者達): Nami and Usopp struggle to stop the addicted children, but Caesar easily defeats them. Caesar then broadcasts himself to the Underworld, revealing his plan to test his new gas weapon on Punk Hazard.
 * 675. Its Name is 'Shinokuni' (その名も「シノクニ」): The children rush to take their drug candy, except Mocha, who resists her addiction and tries to escape. Caesar then lays out a piece of candy which will turn Smiley into Shinokuni, a deadly gas, but Smiley eats it before Caesar tells it to.
 * 676. The Perfected Weapon of Mass Destruction (完全なる殺戮兵器): Smiley effectively dies upon eating the candy and turns into Shinokuni, which instantly encases Caesar's men in an ash-like shell. Zoro, Sanji, Kin'emon, and Brook run from the gas, and Caesar moves his prisoners' cage outside for them to die. Law prepares to initiate a counterattack.
 * 677. COUNTER HAZARD!! (COUNTER HAZARD!!): Eustass Kid and Killer attempt to broker an alliance with Basil Hawkins and Scratchmen Apoo, while Law breaks the prisoners out of the cage. The Straw Hats, Law, Brownbeard, and the Marines reach the laboratory and prepare their counterattack.
 * 678. The Lobby of Laboratory Building A (研究所内A棟ロビー): Shinokuni seeps into the laboratory, and Kin'emon and Zoro lead a party to search for the children, Smoker prepares to fight Vergo, and Tashigi and the G-5 Marines search for the escape route. Luffy goes after Caesar, and easily defeats some of his men.

SBS Notes

 * Franky is stated to have an "infinite amount" of hairstyles.
 * Usopp grows Pop Greens in the Sunny-Go, giving him an infinite supply.
 * Sanji's appearance is revealed to be based off of Steve Buscemi as he appeared in the movie Reservoir Dogs.
 * The ages and heights of the Supernovas are revealed.
 * Oda acknowledges the fact that three cups are shown at Ace's grave, which is later expanded upon.
 * Hina, Smoker, and Tashigi are shown as children.

Usopp Gallery Pirates
In the SBS, a fan tabulated which prefectures each Usopp Gallery Pirates piece has come from, and the top five were 1. Tokyo (219 times), 2. Osaka (143 times), 3. Kanagawa (142 times), 4. Saitama (139 times), 5. Chiba (120 times).