- "I've been trying to find you for over a year. My employer's dying, he wants to thank you for saving his life. It's an honor to meet the Wolverine."
Yukio is a Japanese ninja assassin who is sent to take Wolverine to Yashida, but then develops a strong admiration for him.
When she was 5 years old, Yukio predicted her own parents' death and they soon died in a car accident. She was orphaned until she was discovered by Ichirō Yashida, who had taken his granddaughter Mariko on a trip to view a factory he was opening in the south of Japan. From then on, she was raised by the Yashida family as Mariko's adopted sister and trained as her protector.
After Yashida realizes he is dying, he instructs Yukio to travel the world to find Logan and bring him to Japan. She finds him a nomad living aimlessly in Yukon, Canada, and persuades him to travel to Japan for one day to meet Yashida. Yukio is present at Yashida's funeral ceremony alongside Logan, where the Yakuza attack and attempt to capture her sister Mariko.
Yukio then has a vision of Logan's death. She goes to warn him but is too late as Mariko is captured by the Yakuza who are revealed to be hired by Mariko's fiance and the corrupt Chief of Justice Noburo Mori. Logan and Yukio arrive at Yashida Family Home, where he finds the parasite on his heart, similar to the one inside Yashida's body. He attempts to use his claws to extract it, when Shingen enters mid-procedure and Yukio defends Logan.
Yukio is knocked unconscious by Shingen. Logan briefly dies in the process, but regains his healing ability to fight Shingen. Although he initially leaves Shingen to live with the truth that he ordered his own daughter to die, Logan kills Shingen with his claws after the latter tries to attack him in anger. Yukio and Logan then follow Harada and Viper to the research center to find Mariko. When he arrives, Logan is attacked by Harada and the Yashida family's Black Clan. Logan is subdued by a combination of the Black Clan's arrows and a substance concocted by Viper to weaken Logan as Yukio is helpless to watch.
After Logan is put in a restraining device, Yukio comes to his defense and fights Viper while he fights the Silver Samurai. Yukio kills Viper by hanging her in an elevator shaft.
Wolverine later boards a plane with Yukio, who reminds him that she is still his bodyguard, and offers to fly him anywhere in the world.
- Death Perception - Yukio is a mutant with a limited, precognitive ability to discern the nature of a person's death. Such visions, when and if they occur at all, have a high degree of accuracy. She rarely misinterpets the forseeable future of one person's life. However, she failed once, thinking that Logan was going to die because she saw him holding his heart. It is possible her powers only perceive clinical death and Wolverine was clinically dead and was healed after removing the parasite before he could enter brain death. Also, she cannot foresee faked deaths, such as that Ichirō's.
- Expert Martial Artist/Hand-to-Hand Combatant - Being a Japanese assasin, Yukio is highly skilled in martial arts and hand-to-hand combat, either unarmed or combined with her sword or her staff.
- In the comics, Yukio is human and not a mutant.
- Another deference in the movie is that Yukio has red. In the comics, she has black hair.