|“||I don't give a damn. Friendship isn't real anyway. But how long would you last as my enemy?||„|
|~ Jen Yu to Yu Shu Lien|
Jen Yu is first seen at the residence of Sir Te. She meets and soon becomes friendly with Yu Shu Lien, whom she envies due to being a female warrior that is not tied down by anyone or anything. It is later revealed however, that she is the apprentice of the murderous Jade Fox, and steals the Green Destiny sword for herself, though she later returns it. It is around this time that Jade Fox kills a policeman, followed shortly thereafter by Jade Fox realizing that Jen Yu has been secretly reading the stolen Wudang manual (which the illiterate Jade Fox could not do) and as a consequence has now surpassed her in skill.
Shortly after this, Jen Yu is visited by a man she met in a desert named Lo, with whom she had previously fallen in love with but now believes she cannot be with him. Despairing due to feelings of isolation, Jen Yu steals the Green Destiny again and runs away, intending to live a life of adventure as an arrogant and confrontational tomboy. With the Green Destiny in hand, no warrior is a match for her, as she can simply destroy their weapons. Yu Shu Lien and Li Mu Bai track her down, but Jen Yu has no intentions of relinquishing the Green Destiny or allowing Li Mu Bai to take her to the Wudang. When Yu Shu Lien points out how selfish and insensitive Jen Yu is being, having shown those who are trying to help her nothing but contempt and indifference, Jen Yu declares Yu Shu Lien to be an enemy, leading to a fight between them. As was the case before, Jen Yu is able to get the upper hand simply by destroying any weapon raised against her with the Green Destiny. However, Yu Shu Lien manages to use the sword's invincibility against Jen Yu, ultimately winning the duel. Yu Shu Lien hesitates with her sword at Jen Yu's throat, unable to bring herself to kill her. Jen Yu, bitter at having been defeated, takes advantage of Yu Shu Lien's mercy and cuts her across the arm. Li Mu Bai arrives to witness Jen Yu's shameful act, and pursues her into the forest as she tries to escape. After a chase through the tree-tops of a bamboo forest, he takes the Green Destiny from her. Li Mu Bai tries to get Jen Yu to come with him and become his student, as Li Mu Bai recognizes Jen Yu's potential, but she refuses and instead dives into the water after the Green Destiny after Li Mu Bai discards it. Afterwards she is found by Jade Fox who, now embittered with Jen Yu for having surpassed her in skill drugs her and tries to shoot her with poisoned darts while she is in a delirious state. Li Mu Bai saves Jen Yu and cures her of her drugging, but is shot with one of the poisoned darts before he can kill Jade Fox. Right before she dies, Jade Fox reveals that she was aiming for Jen Yu and spitefully condemns her as being "true poison".
Now remorseful, Jen Yu tries to get Li Mu Bai the antidote he needs, but he expires before she can bring it back to him in time. Afterwards Yu Shu Lien urges Jen Yu to be true to herself no matter what she does in life. Going to the Wudang, she is reunited with Lo, but the morning after a night of passion she goes to the edge of the mountain, overlooking the clouds. Earlier Lo had told her a story of a man who had a wish fulfilled by leaping off the edge into the clouds. Jen Yu asks Lo to make a wish of his own, to which he asks that they go back to the desert together. No sooner does he say this does Jen Yu leap into the clouds.