Yunyun (ユンユン, Yun'yun?) is an eccentric and energetic young girl, and is one of the Borners (the surviving test subjects of Snake's Ua virus experiment). The Ua mutation did not grant her any extraordinary abilities, however, causing her to be treated as a disposable pawn by Liang Qi. A comic-relief who was also made fun of for her almost-flat chest, she was variously tasked with things from spying, (unsuccessfully) infecting Japanese representatives of Shanghai Anti-Terrorism Summit with Ua virus, and (again unsuccessfully) killing Canaan.
Because she befriended Oosawa Maria, however, she hesitated when confronting Canaan and was saved by Canaan in the end. She subsequently tells Minorikawa Minoru about Snake and was hired as his informant. Minoru's party eventually runs into her again on their way to the Factory, where her home village once was and where she intends to spend what's left of her life in. She receives a large quantity of medications for suppressing her Ua virus infection after their brief adventure inside the research complex, however. After the events of the anime, she returns to Shanghai where she continues to work in her part-time jobs.