Mirror Ranma was a copy of Ranma Saotome's female form that was created after she looked into the magic mirror inside the Mirror Mansion. However a second copy of his male form was later created and both copies coexisted before returning to the mirror.
While on a training trip, Genma and Ranma got lost in the rain and stumbled onto the Mirror Mansion. They were welcomed by the innkeeper who warns them not to slip on a banana peel, fly into the forbidden curtain ahead and see the terrible secret beneath it. As he's saying this, Genma ate a banana from a bowl of fruit on a table in front of the mirror and tossed the peel onto the floor, causing Ranma to slip on it and fly into the curtain. She ripped the curtain when she grabbed onto it and fell, exposing the mirror. After Ranma gazed into the mirror, a copy of her emerged, expressing relief at being able to take the form of such a lovely girl. After the innkeeper then explained the mirror's history, the copy tried to run off and hit on as many men as it could, but was restrained. As it would take a week to make a new protective curtain, the copy returned to Furinkan with Ranma and Genma in the meantime.
The first thing it did at the Tendo Dojo was rifle through Akane's drawers, but was disappointed that she had "nothing sexy at all" and that the bras were too small. Ranma was able to come in and tie up the copy, explaining what had happened. However it then fled using a body replacement technique and began to run through the streets of Furinkan, hitting on any eligible-looking man. When Ranma stopped it, it complained that she was ugly, prompting her to show it how to properly pick men up. Both were in the process of doing this when they were stopped by Akane and the copy fled again. It came upon Ryoga Hibiki in the park, who was waiting for Akari Unryu, and kissed him, but just missed his lips. Ryoga was too distraught to fully comprehend that two female Ranmas were right in front of him before fleeing in disgrace when Akari appeared. Back at home Ranma dragged her copy into the bath and anticipated that it would also turn male again, but was surprised when it remained female. The copy then slapped him and playfully rebuked him for not telling her that he was really male. That night Akane saw the copy wearing a negligee and spraying itself with perfume in anticipation of spending the night with Ranma. She chased it into the bathroom where Ranma was brushing his teeth and while on his head called Akane fat, infuriating her. She and Nabiki then camped out in Ranma and Genma's room to keep an eye on both Ranmas, although the copy fell asleep first.
The following morning, the copy shocked everyone by wearing nothing but an apron and preparing a breakfast with a bottle of sake. After Ranma smacked it on the head, Nabiki declared that as a mirror image of Ranma, the copy also had his taste in clothing, which he vehemently denied. The copy was hurt by his words and ran off with Ranma in pursuit. Akane became aware of them after the copy jumped on her head during her morning jog. Wondering how Ranma could not be moved by "such perfect proportions", the copy accused him of liking "stocky, macho, muscle-bound girls". Ranma retorted that he did not like Akane and got smacked by her for calling her muscle-bound. He decided to take the copy to school to keep an eye on her, although on the way she tried to take Akane out with a mallet. At school, the boys of Class 1-F were surprised to find a female Ranma that did not turn male with hot water and asked it to get ramen with them. Ranma stopped the copy from going and questioned its love for him. Although he claimed that he could not love it as a person of the opposite sex despite its being cute and sexy with perfect proportions, the copy told him that it had found the perfect man. Akane concluded by their dialogue that Ranma was a narcissist.
The two left early and Ranma was pursuing the copy when he got splashed by the Old Washer Woman and the copy escaped, resulting in him getting beat up by a furious Ryoga. Akane found the copy at home first, and the latter told her that she was lucky to be loved by Ranma, as it was evident that he preferred barrel bodies and she wanted to be fat like Akane too. Akane chased the copy through the house and it collided with a battered Ranma when he returned, pitching them both into the koi pond. Akane was about to slam the stone toro onto them both when the innkeeper from the Mirror Mansion appeared and stopped her. He presented a magic compact that could be used to contain the copy to prevent it from causing trouble while the new seal curtain for the mirror was made. After an accidental demonstration by Panda Genma, Ranma wakes the unconscious Mirror Ranma and traps her inside the compact, then accidentally gets trapped there herself. Inside the mirror world Mirror Ranma used a tetsubin on her and began to snuggle, which was the position Akane found the two in when she shook the compact to release them. While they argued, the copy escaped with the compact and planned to use it to make her and Ranma eternal lovers.
In order to lure the copy back with the compact, Ranma was trussed up and suspended from a tree in the garden. The copy first ate Ranma's dinner that Kasumi had put out for him and tried to make him look at the compact, but he shut his eyes. The copy used this as an opportunity to try and kiss Ranma but was foiled by Akane's mallet. Soun and Genma then tried to rush her, but were blown away when she used the Hiryū Shōten Ha. However they landed on Ranma (still tied to the branch) and all three fell onto and knocked out the copy. When she revived, the copy pretended to concede defeat to Ranma and Akane's love as a distraction to grab the compact from Soun. She tried to make Ranma look at it again, but he blindfolded himself. She then got Ranma to take the blindfold off by threatening to kill Akane but threw some rice at her face. Akane did not look in the compact when it was offered, but was tricked into looking when the copy claimed that it was broken. When she saw Ranma's expression at this, the copy cried that all she wanted to do was be friendly with him before fleeing. To stop the copy, Ranma resorted to throwing a bouquet of flowers at it which were caught and they went to the park. Here Ranma tried to get the compact out of its shirt, but was tricked by a fake and the copy threatened to bury the compact. After it ran into a statue and got knocked out, Ranma tried to rescue Akane by securing himself with rope to a statue, tree and bench before letting himself get sucked in. When the copy revived it saw Ranma's shoe and the compact together and entered the compact out of jealousy for what Ranma and Akane might be doing, saving him from an attack by Kuno, who had also gotten sucked in. When the compact was thrown into a pond by Josef, a frog looked at it, causing the pond water to inundate the mirror world. The copy tried to drown Akane but is stopped by real Ranma. Then both Ranmas were grabbed by a happy Kuno before knocking him out. Soun was able to recover the compact from the pond and release everything inside. When the copy saw Ranma's concern for Akane, apologized for being such a burden.
After a week, both Ranmas and Akane returned to the Mirror Mansion to return the copy to the mirror. The Ranmas had a poignant goodbye and the copy gave Ranma a gift, which turned out to be the open compact, sucking him in. She tried to run into the mirror with it, but was foiled when Akane threw a bowl of fruit at her and shook Ranma out. However in a repetition of the events the week before that had started the whole incident, he slipped on a fallen banana and again flew into the curtain, ripping it as he fell. However as this time as he remained male, a male copy came out of the mirror vowing to hit on cute girls. However when the two copies saw each other, they both fell in love. They were taken back to Furinkan for another week while another seal curtain was made for the mirror, presumably causing less trouble this time because they had each other.
The first copy was identical to Ranma's female form but lacked his curse. It predominantly wore his long-sleeved Chinese shirt and pants, but once wore a short dress and much more revealing clothing on two occasions. Conversely, the second copy was identical to Ranma's male form.
It also acquired some of his attitudes towards Akane Tendo as well as himself. At first the copy hit on any young man in came across until it discovered that Ranma was really a male. After this it fell in love with him and began to pursue him aggressively.
Both copies have Ranma's abilities. The female was able to use the Hiryū Shōten Ha and body replacement technique, but relied more on creativity and trickery instead of actual fighting ability.
The female copy fell in love with Ranma after learning that he was really a male, but this was one-sided. Although he did not reciprocate its advances, it pursued him relentlessly and was only stopped by the appearance of the second copy. As this was of male Ranma this time, both copies fell in love with each other and left the real Ranma alone.
Because of Ranma's preference and concern for Akane, the female copy saw her as her love rival. However she only seriously tried to eliminate Akane when they were trapped inside the compact and it flooded, otherwise trying to keep Ranma for herself.