The Mirro-World is an alternate dimension that is accessed through mirrors inside Totto Land. Only the user of the Mira Mira no Mi can facilitate entrance and exit from this realm, which they can do by making contact with an intact mirror. However, this is the only privilege the fruit user has over this realm, with anyone inside it being free to do as they please.
The Mirro-World has no defined layout, consisting entirely of a curved floor and walls that have checker patterns on them; the floor is pink and crimson while the walls are light and dark purple. There is also a staircase that goes through the realm. The floor and walls of the Mirro-World are covered in mirrors, each of which are connected to a single mirror in Totto Land. It is unknown if the Mirro-World extends farther than Totto Land or if it ends at all. If a ship enters Totto Land, all of its mirrors will be connected to the Mirro-World as well, and any mirrors created by the Mira Mira no Mi user will also lead to the Mirro-World. While the Mirro-World's dimensions are unknown, the close concentration of its mirrors allows people to travel through Totto Land extremely quickly, and there appears to be no connection between a mirror's location in the real world and its location in the Mirro-World. The mirrors appear to have the same sizes and appearances in both realms.
The mirrors in the Mirro-World are all sentient and can see what is happening in front of them in both the real world and the Mirro-World. They will talk to anyone who talks to them, answering questions as to who and what they see in the real world regardless of the relationship between their acquaintance and the Mira Mira no Mi user. If a mirror in either the real world or Mirro-World is destroyed, then its counterpart in the other realm will also be destroyed, removing that access point.
Charlotte Brûlée, the current user of the Mira Mira no Mi, resides in a house, half of which is in the Seducing Woods in the real world and the other half in the Mirro-World. It is unknown if the placement of the house allows people to enter the Mirro-World through it without Brûlée's help. It has a checker pattern, a tiled roof, and a chimney; there is a water wheel to the right and a smaller house to the left that resembles a doghouse. Inside are many mirrors on the walls, and there is also a giant cooking pot used by Brûlée to cook food.
Whole Cake Island ArcEdit
With her Mira Mira no Mi abilities, Charlotte Brûlée trapped Carrot and Chopper in the Mirro-World after battling them in the Seducing Woods. Chopper and Carrot attempted to explore, but after Brûlée was defeated in the Seducing Woods, she went to the Mirro-World and pursued the duo. After catching them and taking them to her house, she prepared to cook Carrot, and several of her crewmates, including Randolph, Diesel, and the Noble Croc, took part in the festivities. However, Carrot managed to trick Brûlée and elude her grasp, allowing her and Chopper to unleash a surprise attack and take down Brûlée and all her henchmen.
Chopper and Carrot forced Diesel to pull them through the Mirro-World on a cart and Brûlée to explain how the Mirro-World worked. By using Brûlée to let them move through the mirrors into the real world, Chopper and Carrot found all their allies except for Luffy and Sanji, and the cohort left the Mirro-World to reunite with the two of them on Whole Cake Island.
The next morning, the Straw Hats plotted to arrive at Big Mom's Tea Party and wedding through the Mirro-World, and Capone Bege had a mirror be placed inside of the wedding cake. The Straw Hats and the Fire Tank Pirates crashed the wedding and attempted to assassinate Big Mom, but failed, and their plan to escape through a mirror was ruined when Big Mom destroyed it by screaming.
After the wedding chaos, Brûlée was rescued by the Big Mom Pirates, who used her ability to travel through the Mirro-World and lie in wait for the Straw Hats on the Thousand Sunny. However, during the battle that ensued on the Sunny, Luffy saw Brûlée standing on the other side of a mirror and managed to use her ability to pull him and Sweet Commander Charlotte Katakuri into the Mirro-World. As Luffy fought Katakuri, Brûlée and her henchmen attacked the escaping Sunny through its mirrors, and on Luffy's orders his crewmates destroyed all the Sunny's mirrors to cut off access to the Mirro-World.
Luffy was left powerless after using Gear Fourth during his fight with Katakuri, and managed to captured Brûlée and jump into the real world. He traveled to various islands in Totto Land by jumping in and out of the Mirro-World, but eventually returned to the Mirro-World to face Katakuri again. Afterwards, Katakuri's sister Charlotte Flampe and her henchmen came into the Mirro-World to assist him in the battle, and on Cacao Island, Charlotte Oven had all but one of the island's mirrors destroyed in order to ambush Luffy after hearing that he intended to come to Cacao Island. While Katakuri and Luffy fought, Flampe intervened to create an opening for her brother attack to land on Luffy, Only to be scold by Katakuri who has start to see Luffy as an equal and demanded a fair fight with him, matching the wound he gave to Luffy onto himself before continue their fight.
As the hours past, the two traded blows until Luffy decide to activate a new Gear Fourth technique called "Snakeman". With his new form, Luffy is able to somewhat prevent Katakuri from using his future sight by prolonging each attack, However Katakuri soon figure out a way to fight back as the two's attacks meet in an massive clash. After Luffy rise victoriously, Pekoms arrive with a tied up Brûlée, and decide to escort Luffy outside of the Mirro-World. On their way to the mirror on Cacao Island, Pekoms explain to Luffy his plan to be used as an diversion, and his reasoning of fulfilling Pedro's final wish, before jumping out of the mirror with Brûlée as a human shield until his Sulong form is complete.
- The mirrors inside the Mirro-World answer when being questioned, similar to the magic mirror from the fairy tale "Snow White", which matches the Big Mom Pirates' theme and Brûlée's similarities to the Evil Queen in particular.
- This is one of two known alternate dimensions in the world, the other being the dimension accessible through the Doa Doa no Mi's Air Door. Unlike that dimension, the Mirro-World does not have to be accessed by the Mira Mira no Mi user performing an action, although it can be if the user creates a mirror.
- Interestingly, the mirrors counterparts inside the Mirro-World are mirrored version of the real world mirrors.