Nagisa Nagase, also known as Yasha, is a central character in the story who begins as a waitress at the Marine House seafood restaurant on the Shonan coast. She comes from a well-off family and attended the private Shonan Fujisawa Girls' Institute. Her life was shattered when she was kidnapped, abused, and raped by Junya Akutsu, the second-generation leader of the Midnight Angel biker gang. This trauma caused her to develop dissociative identity disorder as a psychological defense mechanism. To cope with the abuse, she created a separate and violent alter ego named Yasha, who genuinely loved Akutsu and mirrored his cruelty. When Yasha takes control, a traditional hannya demon tattoo appears near her left shoulder, and she rides a black Kawasaki Eliminator motorcycle marked with a Midnight Angel sticker. In her Nagisa personality, she is gentle, sweet, and appears to be a normal, innocent young woman with no memory of Yasha's actions. She is often confused and frightened when she wakes up with blood on her clothes or finds herself in dangerous situations she cannot recall. Her primary motivation is to live a peaceful life and escape her traumatic past, but she is also driven by a deep, genuine love for Ryuji Danma and a desperate desire to be saved from her condition. She struggles with self-loathing and guilt over Yasha's violent acts, and at one point she even attempts suicide by stepping in front of a car because she believes she is a danger to everyone she cares about. In the story, Nagisa serves as both a romantic interest for Ryuji and a significant challenge for the Oni-Baku duo, as Yasha's rampages threaten the fragile peace of the Shonan delinquent world. Her role is pivotal in the Midnight Angel story arc, during which Yasha returns to help Akutsu rebuild the gang and seeks to eliminate Ryuji and his allies. Her key relationships are with Ryuji, who falls in love with her gentle side and promises to save her from Yasha, and with Akutsu, who remains Yasha's object of violent loyalty. The internal battle between Nagisa and Yasha forms the core of her character development. Over the course of the story, Nagisa gradually gains the strength to fight back against her alter ego, and in the climax of the Midnight Angel arc, she manages to briefly take control and protects Ryuji by taking a knife meant for him. After a near-death experience in a cabin fire and a long hospitalization, she finally overcomes Yasha and becomes Ryuji's official girlfriend. In her later appearances, she continues her relationship with Ryuji, and the two eventually live together in an abandoned bus with the help of their friends. Her notable abilities include her skill as a motorcycle rider and her surprising physical strength when Yasha is in control, as Yasha is capable of beating multiple gang members into submission without weapons. After her recovery, Nagisa is shown to be a capable and caring partner, and the couple remains together into adulthood, as seen in later appearances in the Great Teacher Onizuka timeline.