Yū stands among three close high school friends of protagonist Tamahi. She witnesses with the group an individual's fatal fall from a nearby apartment rooftop during their walk home. Driven by the incident, Yū joins Tamahi and their friend Aki in rushing to investigate the building.

Inside the complex, Yū experiences shared auditory hallucinations and sensations of being watched. She becomes trapped alongside her friends within the structure's warped reality, where time and space distort unnaturally. Yū actively participates in escape attempts while confronting escalating supernatural phenomena.

During their ordeal, Yū and her friends encounter infernal entities described as ghost bugs or infernal bug creatures. These beings seek human bodies and souls, specifically targeting the schoolgirls as vessels for interdimensional passage. Yū endures the collective experience of being hunted by these creatures within the apartment's monstrous parallel dimension.

The narrative provides no distinct personality traits or individual background for Yū beyond her role within the friend group. Her experiences unfold collectively with Tamahi and Aki, positioning her as one component of the trio trapped in supernatural conflict. No further official appearances or developments for Yū in other media exist within the provided information.