Yuuka serves as a central character in the OAV "Zero Sum Game." She is romantically involved with Yazaki, whose brother Keith fronts the band "Zero Sum." Keith invites Yuuka and Yazaki to a concert, granting them backstage access. After the show, band members excluding Keith kidnap Yuuka. On a rooftop, they sexually assault her, an attack orchestrated by Keith driven by his obsessive feelings for his brother. The assault inflicts profound psychological trauma on Yuuka. She remains unable to forget the incident or escape its emotional repercussions. The narrative centers on the immediate aftermath, depicting Yuuka's ongoing struggle with this trauma.