Natsumi Ueno is a university student and a supporting character in the crossover film Sadako vs. Kayako. She is the best friend of the protagonist Yuri Kurahashi and is characterized as cowardly, funny, and kind. She has short hair and is approximately the same height as Yuri. Natsumi's role in the story begins when she and Yuri acquire a used video player that contains the cursed videotape created by Sadako. While Yuri is distracted by her phone, Natsumi watches the entire tape alone, thereby activating Sadako's curse and starting a two-day countdown to her death. Her immediate motivation is a fear of dying alone, which drives her to upload the cursed video to the internet and later delete it. As the deadline approaches, Natsumi becomes increasingly despondent and blames Yuri for her predicament. She attempts suicide by strangling herself to escape the impending death, but Sadako appears and kills her by hanging before Yuri can intervene. Natsumi's key relationship is with Yuri, who tries to save her by watching the tape herself and attempting to assume the curse. Natsumi's death demonstrates Sadako's inescapable curse and propels the plot toward the planned confrontation between Sadako and Kayako. She does not possess supernatural abilities; her significance lies in being a victim whose actions spread the curse and test the desperation of the other characters. She shows minimal development beyond her initial fear and brief blame toward Yuri, as she dies early in the film.