Ren Fa is Akira Uduo's girlfriend. They met during a raid by the Wind G-men. The police were trying to stop a group of smugglers. One of the smugglers, Ren's brother, carried a suitcase. Ren was nearby at the time, and apparently the smugglers ran into a building with her. Akira killed (or maimed, it is unknown) all of the smugglers, including Ren's brother.

(Source: Air Gear Wiki)