Chrona was created in a Japanese laboratory by a team of scientists in the year 3000. When she was created the other team of scientists made a bet to see who could make the first ever robot with a human brain to use it as a model for making the next generation of Earth as it was predicted that the human race would die out in 5 years. So one group worked hard to make Chrona (Team Chrona) while the other made her "brother", Chrono 0.0 (Team Chrono).
Unfortunately Team Chrono won and was used as a model in order to make the next generation of Earth.Team Chrona didn't know what to do with Chona since she had served her purpose so decided to create a new one for her by making her the first robot with animal DNA or a Mew Mew. The project was named "The 2nd Mew Experiment" and was quickly started up. During then Chrona still found time to talk to Chrono and they became close, stopping to talk to him when she saw him. 4 years of research went into it until the experiment was ready to be tested on Chrona. She became confused and scared but after talking to Chrono she became more confident and went through with the project.
Chrona became the first ever robot with the DNA of a computer generated tabby cat. Once the experiment was complete she was given a remote which would change her into a Mew. The team of scientists decided to keep quiet about this knowing there would be people who would want to get their hands on her especially since they had become attached to her. Chrono, who had become jealous of his sister's upgrade revealed anonymously to the world that a robot with the DNA of a cat had been made in the laboratory. A evil, power hungry scientist called Dr. Aku (aku=evil) who wanted to have the world rid of humans since that it was all their fault the Earth was becoming dangerously polluted, decided to take Chrona in order to achieve his dream of ridding the world of the "vile, evil" humans.
To get her, he attacked the laboratory with his highly intelligent army robots (H.I.A.R) who had very advanced weaponry for the time but Chrona was still stronger than her. He killed everybody who was part of Team Chrona but luckily Chrona escaped by fighting the robots but with her leg badly injured in the end. Aku was so angry that Chrona had escaped that he sent the H.I.A.R's to kill every human they could find, in a fury of rage. He created more H.I.A.R's until his dream had been achieved but by then he had went mad over wanting to get Chrona so badly. Chrono discovered that the lab had been destroyed after hiding and Chrona was missing so he set off to look for her.
Chrona, with her leg almost gone and losing her memory fast (due to her memory chip being broken when she was confronted by the H.I.A.R's) wandered around for days looking for help and soon fell in into hibernation mode for a year, which stored some extra external battery energy from the little she had left. When she awoke, finally found help at the old, run down Café Mew Mew where she found 3 teenagers named Dylan, Junpei and Nana. At first they thought she was one of the H.I.A.R's and thought that they should attack but then realized that she was the cat robot that had driven Aku insane and the one thing H.I.A.R's had been programmed to look for. They took her in and and fixed her leg but by then Chrona had already lost her memory as it could not be fixed as it had to have been removed so she would have more power. They decided she was the only one who could stop Aku and decide to train her in martial arts which Dylan knew, so she could defeat Aku. Years went by and Chrona had a happy "childhood" with her "family" while Chrono continued to look for Chrona, beating himself up for her disappearance.
When the time came for her to go up against Aku they realized if they should tell her as they thought her as family. Chrona overheard their conversation and felt upset and confused so she ran away. The H.I.A.R's kidnapped her and took her to Aku. Her friends and Chrono found this out and got there as quickly as they could. By the time they got there she had her memory chip removed, as Aku had overpowered her and was about to insert his own memory chip which had instructed her to destroy all humans (as he was unaware he had destroyed pretty much all of them). They attacked him and he was killed by Dylan, Junpei, Nana, Chrono and Chrona's Mew powers all put together. But by then Aku had dropped the original memory chip and broke it and Chrona's circuits had also gone on fire. Her friends and brother tried their best for days to reboot her to her normal self.They realized that the only way to get her back was to create a new memory chip and help her remake her memory while also putting some of Chrono's memory on it too to help her remember. Chrona spent years with her family slowly getting her memory back and as she did she felt sad that there was only 5 people living on Earth. Chrono remembered the robots that were being built years ago. He rushed to the lab and activated the remaining robots. Chrona felt happy that there was once again more people on Earth.
Tokyo of the year 3000 and up, The Global Warming Incident of 2054
Chrona grew up in Japan along with Chrono, Nana and Junpei (except for Dylan who grew up in America before the Global Warming Incident of 2054). Japan is the only suitable place for humans as of The Global Warming Incident Of 2054 as every country either became too hot or too cold for human life to live on due to global warming. Most people who manged to escape to Japan now live there but due to not everyone being able to get there the population of Earth is now 899. The population of Earth slowly began to fix and adjust to everything just before Aku attacked with his H.I.A.R's.
In her normal form Chrona has nails on her head, long pink hair and screws on her body. In her Mew form she has black cat ears and tail with a blue ribbon on it, long red hair, her face is half metal, blue boots, grey arm plates, and a dark blue coat with screws for buttons.