They are both allies of the Straw Hat Pirates during the end of the Water 7 and beginning of the Enies Lobby Arc (starting off as minor antagonists in the former). Currently, they jointly manage a bar.
Although they are not twins, Mozu and Kiwi are identical in all but hair (Mozu's not as curly as Kiwi's) and eye color (Mozu has a brownish hue while Kiwi's is green). They both have long, pointed noses and get their nickname from having a unique hairstyle shaped in large squares. When they were younger, they wore their hair in afros.
Mozu is the sister with straight-edged hair, a white fur collar, yellow goggles, bikini-top, slacks, and high-heels.
Kiwi is the sister with curly-edged hair, a lilac pearl necklace, pink cropped top, pink bikini-bottom, gloves, and high-heels.
Mozu and Kiwi are classic sidekicks; they stay in the background and chime in every once in a while. They have a tendency to mimic Franky's actions and reactions. They also seem to have a strange habit of doing odd poses when in the background, and generally act like Franky's back up singers, even if he isn't singing. They also have a sense of sassiness.
They often move in perfect sync, like mirror images of each other. Whether they do this on purpose or if it just happens naturally is unknown.
They often walk sideways in high winds, due to the fact that otherwise their hairstyles would catch the wind like a sail and cause them to be blown back. They both also have a tendency to add "Waina" to all their sentences, which they have done ever since they were young.
Abilities and Powers
During battles, they fight with katana swords with square-shaped tsubas. They are accomplished swordswomen, quick with a blade, and skilled enough to take on foes such as the Just Eleven Jurymen and win. However, they are not powerful enough to subdue stronger fighters like Franky and Kalifa.
- Sentei Kaitai Giri (船底解体斬り? literally meaning "Ship's Bottom Dismantling Cut"): Kiwi and Mozu run on either side of their target and coordinate their strikes to make symmetrical cuts along said target. It was seen used on Kashii's left shoe. This is called Hull Dismantler Slash in the Viz manga.
Twelve years ago, after Tom's Workers completed the Puffing Tom, Mozu and Kiwi rode the Sea Train on its opening day. They were inspired by this event and tried to be shipwrights; however, they failed the Galley-La company tests and began drinking heavily. They were then found by Franky and started working for him after he encouraged them to stop drinking.
Water 7 Saga
Water 7 Arc
In the Franky House, Mozu and Kiwi stood at Franky's sides while he counted money that the Franky Family stole from the Straw Hat Pirates. After Franky beat up Usopp, who had come to take back the money, Mozu and Kiwi followed Franky out the door. They boarded the Sea Train and went shopping with the stolen money. The next day, when they returned from their shopping trip, Franky and the sisters were shocked to find the Franky House in ruins. Zambai informed them that it was the Straw Hats who destroyed the building and that they will be at Dock 1, so Franky and the sisters went to the closed dock to confront Monkey D. Luffy and Nami. The sisters mimicked Franky's poses and then cheered Franky on as he fought Luffy. The sisters were disgruntled by the Galley-La employees' interruption of the fight. While the shipwrights attacked Luffy, Franky and the sisters sat by and had tea before flipping the table in outrage over the continued interference in Franky's fight with Luffy. After Franky's Coup de Vent destroyed Dock 1, the sister questioned if Franky was going to pursue Luffy, who had escaped in the destruction, but Franky needed to refuel first.
Afterwards, the three visited Blueno's bar, and Franky refilled on cola and dispersed the remaining stolen money to the other patrons. The sisters enjoyed their own drinks, while Franky talked with Kokoro. The sisters were confused when Franky smashed the counter in frustration, but they followed him as he stormed out. As they left, Kiwi thanked Blueno for the drinks. As the Aqua Laguna approached, the strong winds forced Mozu and Kiwi to walk sideways. They reconnected with the rest of the Franky Family, and Franky planned to kidnap Usopp in order to lure out the other Straw Hats. Franky and the sisters took Usopp and the Going Merry to their secret warehouse under the bridge. They cried after hearing Usopp's story about leaving the Straw Hats, but cheered up when Franky tried to turn it into a song. After Franky and Usopp agreed to put aside their past transgressions against each other, Franky offered Usopp a position as a ship demolisher, but Usopp refused since he was still a pirate. Kiwi served tham all tea, while Franky and Mozu explained the Aqua Laguna, Water 7's fate, and the Sea Train. Franky and Usopp then got into a fight over dismantling the Going Merry. The sisters were shocked by Franky's harsh treatment of Usopp and Merry, and began crying alongside Usopp during the discussion of Klabautermann.
Afterwards, CP9 rang the doorbell of the warehouse. The sisters thought it was the rest of the family bringing the Straw Hats to them. When they answered the door, both sisters were knocked down, with Kalifa taking down Kiwi with a kick to the neck.
Determined to save the abducted Franky, the sisters and the rest of the Franky Family tracked down the Straw Hats and begged to join Luffy on the Rocketman. Luffy accepted so the Franky Family attached their King Bulls, Sodom and Gomorrah, to the rear of the sea train. After the train found the tracks, the sisters and Zambai attended a meeting in the rear compartment, where the Straw Hats, Franky Family, and Galley-La shipwrights agreed to work together. When the train faced crashing into the Aqua Laguna wave, Luffy and Roronoa Zoro punched and slashed a hole through the wave, which greatly impressed Mozu and Kiwi, along with everyone else. Later, after Nami changed clothes in front of everyone, Mozu and Kiwi teased Paulie, who complained about the women's immodesty.
While bored on the train, the sisters participated in a reenactment of Luffy and Zoro splitting the Aqua Laguna wave. When the Rocketman came upon the Puffing Tom's discarded train cars, Zoro cut the cars in half, which completely shocked the sisters. As the train continued, the sisters were worried to learn that "Ship Cutter" T Bone was standing ahead on the tracks. However, Zoro defeated the Marine Captain, and the sisters celebrated and praised Zoro. When Yokozuna jumped onto the track, Luffy demanded that the train turn around, which confused the sisters and the others.
Enies Lobby Arc
Yokozuna knocked the train off the track and separated the train from the Franky Family's ship. Kokoro and Nami managed to navigate the train and locate the Franky Family, and then continued on to Enies Lobby. As they approached the island, the Franky Family, Straw Hats, and Galley-La workers laid down their plan of attack. Usopp introduced himself as Sogeking, but the sisters saw through the disguise. The Franky Family and Galley-La workers volunteered to go ahead and force open the two gates so that the Straw Hats could ride the train through. They fought their way through the Marines and opened the main gate, but when they reached the island gate, they were confronted by Oimo and Kashii, the two giant gatekeepers.
After a fierce combat, and with the aid of Galley-La, they manage to bring the giants down, open the gate and lead the way for the upcoming Straw Hat pirates. The team, riding the giant King Bulls, advances towards the inner section of the island defeating foe after foe, until they reach the courthouse. There, they split in two groups in order to lower the bridge to the tower of justice. Each sister takes the lead of their respective team and advance, facing various enemies and traveling up the towers.
Out of nowhere, a few members of the Just Eleven Jurymen attack the twins and their cohorts and engage in a battle. After some struggle and the help of Tilestone and Peepley Lulu, the groups manage to overcome the Jurymen and proceed onward. When the two teams reach the switches and finally start lowering the bridge, the defenses fire a barrage of cannonballs causing the mechanism to malfunction and prevent the bridge from lowering all the way. Eventually, both Mozu and Kiwi, as well as all the other raiders get captured and tied.
When they, finally, manage to escape their bonds with the help of Paulie, they were shown shocked to hear the news about the upcoming Buster Call on Enies Lobby. As the Warships arrive, the Franky Family are desperately trying to escape the island before its destruction begins, hoping that their boss will make it out safe somehow too. Upon reaching the coast, the Franky family come across the warship led by Vice Admiral Strawberry, who orders his men to attack the criminals. The team gets bombed and thrown off a cliff but are all saved at the last minute by Paulie's ropes. When the Straw Hat pirates draw the attention of the marines, the sisters follow their team aboard the sea train, thus escaping the burning island.
Post Enies Lobby Arc
They appeared again in the Post Enies Lobby arc, where they accompanied Franky to visit the Straw Hats to inform them of their leader's decision to build them a new ship. They then bore witness to the sudden appearance of Vice-Admiral Garp whom they were shocked to learn is Luffy's grandfather and became even more surprised to learn that Luffy's father was Revolutionary Dragon.
They are shocked again, to learn that Franky now has a bounty and feared for what will happen if he stayed in Water 7 since everyone knew of him. Later on the two see Franky off, and were horrified when Nico Robin attempted to force him to join by squeezing his testicles, claiming that they would fall off like a piece of fruit from a tree.
After the Straw Hats' departure, the sisters, along with the other members of the Franky Family, were offered jobs by Iceburg, whom they started calling their new "Big Bro" as thanks, much to his annoyance.
Fish-Man Island Saga
From the Decks of the World
Four Emperors Saga
From the Decks of the World: the 500,000,000 Man Arc
When Franky's new wanted poster reached Water 7, Mozu and Kiwi smiled while looking at it with Iceburg.
Cameos and Crossovers
- The Square Sisters appeared as one unit in the game Jump Ultimate Stars for the DS. Though not playable, their character evolution allows a version of Franky to become playable.
- Concept artwork from Color Walk 4 shows that Kiwi's hair was originally spiky and Mozu's hair was wavy, before Oda decided to turn their hair style into a square shape.
- Kiwi is named after the Kiwi bird, while Mozu is named after the Bull-headed Shrike, or in Japanese, Mozu. This is part of a long-standing tradition from Oda to name female characters after birds.
- In the 4th Japanese Fan Poll, Mozu and Kiwi are both ranked as the 122nd most popular characters.