Note: History is inferred based off what can be translated, and may not be entirely accurate.Not much about Rin's past is known, except for her track record as an assassin and fully-trained Pilot to the point that she is often listed as a potential suspect in any high-profile assassination on the Frontier. However, all attempts to find her have failed due to lack of evidence - though she is known to employ a customised Stryder-class Titan.
Eventually, Rin attempted to show off her skills by leading an assassination attempt on multiple core IMC personnel, leading to parts of her past being exposed. According to the information revealed, she is a survivor of a covert human enhancement project that had been pursued in the past. However, the experiments failed and now she exacts revenge on those involved in the project.
She cooperates with others who can help her in some way, but still likes to move on her own. Her outstanding assassination skills and maneuverability with a Stryder are hallmarks of her assassination style.