Waai Fu is the daughter of the famed martial artist Huai Tianpei who, out of his craze for kung fu, abandoned her to go on a solo journey across Yan. Following his sudden departure, she was brought under the care of Mr. Lee, the founder of the Lee's Detective Agency, whom she will treat as her step-uncle. While studying in a university and living a simple life in Lungmen, Waai also joined Rhodes Island as part of an agreement between R.I. and the Agency.

(Source: Arknights Wiki)