Ninja-Pirate-Mink-Samurai Alliance

The Ninja-Pirate-Mink-Samurai Alliance is a pirate alliance originally formed between the Straw Hat Pirates and the Heart Pirates with the goal of taking down Kaido of the Yonko.

However, Law's real goal was to take down Donquixote Doflamingo of the Shichibukai in order to avenge his friend Donquixote Rosinante; he intended to end the alliance when Doflamingo broke their agreement and die taking Doflamingo down if necessary. However, Luffy refused to allow the alliance to end, and their goal is now actually Kaido as Kaido will now target them due to their involvement in Doflamingo's downfall.

When the two crews arrived on Zou, however, the alliance grew to include the Kozuki Family of Wano Country, led by its young heir Kozuki Momonosuke, and the Mink Tribe, whose leaders Inuarashi and Nekomamushi were servants to the Kozuki Family.

Past
Thirteen years ago, a dying Trafalgar D. Water Law joined the Donquixote Pirates. Donquixote Rosinante, better known by his codename Corazon, tried to help cure Law of his illness. During their mission, he revealed that he was a Marine Commander intent on bringing down his brother Donquixote Doflamingo. However, Doflamingo discovered what was going on and killed Corazon, traumatizing Law. Afterwards, Law swore to gain revenge.

In preparation for the alliance, Law left his crew on Zou a month ago while he set off for Punk Hazard to form a partnership with Caesar Clown.

Sometime during or shortly after the timeskip, the daimyo of Kuri Kozuki Oden and his wife were killed by Kaido and the shogun of Wano Country as the two sought out a secret Oden knew. Oden's son, Momonosuke, and his retainers Kin'emon, Kanjuro, and Raizo, were able to escape the country. The samurai sailed to Zou in order to recruit allies, but were shipwrecked, causing Raizo to be separated from the group. Raizo ended up on Zou, while the others landed on Dressrosa. They were chased by the guards, and Momonosuke stowed away on a ship headed for Punk Hazard. Kanjuro sacrificed himself so Kin'emon could head to Punk Hazard, as Momonosuke was put in a testing facility there. Momonosuke unwittingly ate Vegapunk's Artificial Devil Fruit, and fell into the garbage chute after being chased by the guards. Kin'emon arrived on Punk Hazard when he encountered Law, who split him into three pieces which became scattered across the island.

Punk Hazard Arc
When the Straw Hat Pirates landed on Punk Hazard, they discovered the pieces of Kin'emon's body as they explored the island and eventually succeeded in putting him back together. Nami, Sanji, Chopper, and Franky encountered Law when the pirate was battling Smoker and the Marines, and Law switched their bodies around.

Later, Law defeated the Yeti Cool Brothers which the Straw Hats were battling, and offered to form an alliance with them to take down Kaido. The Straw Hat captain Monkey D. Luffy agreed, despite Law warning him that their chances of success were only around 30%, and their alliance was formed. Law's first objective was to destroy the SAD production and capture the man in charge of production, Caesar Clown, in order to hold him hostage to his master "Joker", better known as the Shichibukai Donquixote Doflamingo. The pirates succeeded in their mission, also defeating Vergo and Monet of the Donquixote Pirates. Kin'emon also sought to rescue Momonosuke, and Luffy found him in the garbage dump.

After the alliance thwarted an attempt to reclaim Caesar by Buffalo and Baby 5, Law revealed to the Straw Hats that Kaido relied on artificial Devil Fruits known as SMILE to build an army of Zoans, and these SMILE were provided by Doflamingo. Law's plan was to use Caesar as a hostage in order to force Doflamingo to quit the Shichibukai, as without Caesar, he could no longer make SMILE. If Doflamingo agreed, Caesar would be returned, but the alliance would infiltrate Dressrosa in order to destroy the factory producing SMILE. This would ensure that Doflamingo faced Kaido's wrath while Kaido would be cut off from his source of power.

Dressrosa Arc
The next day, Doflamingo's resignation from the Shichibukai was reported in newspapers, and the alliance arranged a deal for Caesar's return.

The alliance sailed to Dressrosa, where they split up into three groups: Law, Robin, and Usopp will take Caesar to Doflamingo, Luffy, Zoro, Sanji, Franky, and Kin'emon will find and destroy the SMILE Factory, and Nami, Chopper, Brook, and Momonosuke will guard the Thousand Sunny. Kin'emon also sought to find the captured Kanjuro. However, Luffy entered the Corrida Colosseum in order to participate in a tournament for the Mera Mera no Mi, as Doflamingo created this as a trap for him.

The Caesar Return team made their way to Green Bit to return Caesar to Doflamingo. However, Sanji discovered that Doflamingo had tricked everyone and that he never quit the Shichibukai. It was too late, though, as Marine Admiral Fujitora accompanied Doflamingo to battle Law. As the battle began, Robin and Usopp discovered a tribe of dwarves who were revealed to be part of a movement set on bringing down Doflamingo. Franky and Zoro also met dwarves on Dressrosa as well as a toy named Thunder Soldier, and they discovered that Doflamingo ruled over Dressrosa by turning every dissenter into a toy, which would cause them to be forgotten.

Meanwhile, the Sunny team came under attack by Jora of the Donquixote Pirates, and were turned into living art by her. However, Brook succeeded in tricking and defeating Jora, but the crew found themselves sailing toward Green Bit. Doflamingo and Fujitora defeated Law on the island, but Law managed to escape. As Doflamingo chased him, however, he decided to attack the Sunny. Sanji arrived to stop Doflamingo, but was easily defeated, and Law intercepted the Shichibukai. Law told the Sunny crew to take Caesar to Zou while he held off Doflamingo. Sanji, however, questioned Law's fixation on Doflamingo, as their only goal was to destroy his factory. As they faced off, Law revealed to Doflamingo that he only made the alliance to destroy Doflamingo's SMILE so that Kaido could kill him. His main goal was not Kaido, but to avenge Corazon's death and die in the process if necessary, so he ended the alliance.

Doflamingo defeated and captured Law, taking him to his palace. Meanwhile, the Sunny crew came under attack by the Big Mom Pirates, and Luffy told them to head for Zou. Luffy was freed from the Corrida Colosseum by Sabo, and he, Zoro, and Kin'emon accompanied the former Donquixote Pirate Viola to the palace in order to rescue Law. At this time, Franky, Robin, and Usopp learned of the plan to free all the toys by knocking out Sugar, the one with the power to make them. As Franky distracted the guards outside, Robin and Usopp infiltrated the underground harbor with the dwarves. They located Sugar, but she and her guard Trebol easily overpowered them and turned them into toys. Usopp was the only one left standing, but after a final stand, he was defeated. However, when Sugar decided to torture him, she caused him to make a terrifying expression, scaring her into unconsciousness.

Luffy's group reached the outside of the throne room, and Thunder Soldier came there as well. Upon returning to his human form, a man known as Kyros, he rushed in and decapitated Doflamingo. However, that Doflamingo turned out to be a clone, and the Straw Hats rushed in to confront the real Doflamingo. Law told Luffy that their alliance was over and that they were now enemies, but Luffy ignored him and tried to free him. Doflamingo defeated Luffy and Pica ejected Luffy's group, Law, Kyros, and former king Riku Dold III from the palace. Doflamingo then used his ultimate technique, the Birdcage, which trapped everyone inside Dressrosa.

Pica rearranged the structure of Dressrosa, sending the palace far away from Luffy's group and putting the SMILE Factory aboveground. He then inhabited a large golem and attacked Luffy, Zoro, and Law. With the help of the allies Luffy made in the Colosseum, Luffy, Zoro, and Law ascended up to the palace's new location, with Zoro staying behind to confront Pica. Kin'emon also found Kanjuro inside a deep pit where prisoners were put, and they managed to escape. Meanwhile, Franky and the dwarves attacked the SMILE Factory, but Franky was forced to battle Senor Pink at the entrance. Finally, Luffy and Law made it back to the palace and confronted Doflamingo again.

Doflamingo and his subordinate Trebol used wily tactics to split Law and Luffy up, and Doflamingo brutally injured Law. As this happened, the Straw Hats and the Colosseum gladiators defeated the Donquixote Pirate officers one by one. Once Senor Pink was defeated, the dwarves destroyed the SMILE Factory. Doflamingo decided to destroy Dressrosa by closing the Birdcage, but after a great effort Luffy and Law managed to defeat him.

Doflamingo and his crew were arrested and Fujitora ensured that the news of the alliance's victory was released to the world, which earned the alliance instant notoriety. Sakazuki ordered Fujitora to capture Law and Luffy, and the Admiral attempted so three days later. However, they managed to escape, and the Colosseum gladiators that had fought with Luffy pledged their allegiance to him, forming the Straw Hat Grand Fleet. The Straw Hats and Law all had bounty increases, although Sanji was notably only wanted alive.

Invasion of Zou
While this happened, Jack and the Beasts Pirates attacked the island of Zou in search of Raizo. The native Mink Tribe refused, and a five-day battle ensued. Eventually, Jack won after using the poisonous gas Koro to subdue the minks. However, he was forced to leave after hearing the news of Doflamingo's defeat.

The same day, the Sunny crew arrived, drove away the remaining Beasts Pirates, and healed the minks. As Zou healed, however, the Big Mom Pirates caught up to the Straw Hats with orders to take Sanji, as he was arranged to be married into Big Mom's family. Sanji allowed himself and Caesar to be taken, but ensured that everyone else was freed.

Zou Arc
Two days later, the remaining Straw Hats, Law, Kin'emon, and Kanjuro reached Zou, but Kin'emon and Kanjuro were initially unable to reach the top of the elephant it was located on. The Straw Hats met with the minks and reunited with the rest of their crew as Law reunited with his crew. That night, Luffy met Law's crew as he and Law discussed the alliance's plans for the future.

Having heard about Jack's invasion, the Straw Hats were determined to prevent the samurai from reaching Zou, under the impression that there would be bad blood between them and the minks. They were unsuccessful, but it was revealed to them that the minks were allied with the Kozuki Family and that they risked their lives to protect Raizo. Kin'emon also revealed that he was not Momonosuke's father and that Momonosuke was the son of the daimyo Oden.

The Straw Hats and Law were taken to see Raizo, and the samurai told the Straw Hats about Oden's death and Kaido's occupation of Wano Country. After being encouraged by Luffy, Momonosuke begged the pirates to help them in the fight against Kaido, which Luffy agreed to. The Ninja-Pirate-Mink-Samurai Alliance was then officially formed.

The alliance made plans as to their next course of action: Luffy planned to go to Whole Cake Island with Nami, Chopper, and Brook to rescue Sanji, while Zoro, Usopp, Robin, Franky, the Heart Pirates, and the samurai would head to Wano Country. Meanwhile, Inuarashi and Nekomamushi planned to look for the missing Marco the Phoenix in order to increase their alliance's strength.

The elephant carrying Zou, Zunisha, came under attack by Jack and his men, but on Momonosuke's command, it wiped out his entire fleet. With everything settled, the alliance split up and began their missions.

Alliance Strength
When the Heart Pirates and Straw Hat Pirates formed an alliance, it was immediately reported the next day. The captains, Monkey D. Luffy and Trafalgar Law, are both part of the infamous group known as The Worst Generation, having earned bounties of 400,000,000 and 440,000,000 respectively at the time of the alliance's formation. Both captains also have Devil Fruit powers. Luffy is well noted for invading all three main World Government facilities and escaping from all of them alive, with Law helping him escape from Marineford. Law is infamous for taking part in the Rocky Port Incident and later sending 100 pirate hearts to the World Government, earning him a Shichibukai position and immunity from the Marines until it was revoked after the events on Dressrosa. Upon deducting what their plan was, Fleet Admiral Sakazuki decided to send a Marine Admiral to deal with the alliance, indicating the threat they posed, as Law was able to defeat Vice Admiral Smoker, a Logia user, with relative ease.

Upon their alliance's formation, Law stated that they still paled in comparison to a Yonko, as he stated that their chances of taking down Kaido together were only 30%. However, since Law did not originally intend to actually battle Kaido, the statistic is uncertain. The alliance's notoriety grew significantly when they took down Doflamingo, a powerful Shichibukai, and his entire crew the day after their formation. This action was so shocking to the World Government so much that Sakazuki attempted to cover the information up, but Admiral Fujitora did not let him. Luffy and Law both earned bounties of 500,000,000, with the Straw Hat Pirates' bounties all increasing as well. Not only that, but seven crews of notable warriors, composing over 5000 people, that Luffy allied with on Dressrosa pledged their allegiance to him, which drastically increased the alliance's power.

The alliance's power only grew as it expanded to include the Kozuki Family and the Mink Tribe. The minks are all born warriors, with the ability to produce electric shocks known as Electro. The Mink Tribe's warriors were able to fight on par for five days with Kaido's right hand man Jack and his subordinates, and managed to gain the upper hand, only losing when Jack used the gas Koro. The minks are also stated to have another special ability, though this has not been shown. The three samurai retainers of the Kozuki Family are all trained in combat, with Kin'emon and Kanjuro being swordsmen and Raizo using ninjutsu. Kin'emon and Kanjuro also have Devil Fruit powers. Their leader Momonosuke, although he is young and inexperienced, possesses an Artificial Devil Fruit power as well as the ability to communicate with the enormous elephant Zunisha, which is capable of wiping out large fleets.

Trivia

 * Luffy was the one who came up with the alliance's name, causing one to question why the "Ninja" part was needed as the ninja, Raizo, was affiliated with the samurai. However, the consensus was that it was needed.
 * There are four different groups in this alliance, making this the largest known number of allied groups.