Ayane Yagi is a minor character from the film Battle Royale II: Requiem, serving as one of the students from the third-year Class B of Shikanotoride Junior High School forced to participate in the government's program. She is assigned as female student number nineteen. Before her abduction to the military facility, Ayane lived a troubled life in her local town. During her elementary school years, she was a victim of sexual harassment by a teacher, a traumatic event that caused her to boycott school for a significant period. Despite this difficult background, she eventually joined the basketball club in junior high school. She formed a close-knit local group with her friends Kana Yuki and Eri Yoshiyama, with whom she shared a strong bond. Ayane also developed romantic feelings for her male counterpart, Tatsuro Morishima, and confessed her affection to him on several occasions, but she was rejected as he had no interest in girls.

Ayane is portrayed as a protective and loyal individual, particularly towards her friends. When the class is held in a caged room and their teacher, Riki Takeuchi, reveals the deadly nature of the program, Ayane instinctively tries to shield the frightened Kana Yuki, who hides behind her for safety. In another moment of solidarity, she grabs Shiho Matsuki when the other girl returns from the designated winner side of the room to join the rest of the class on the losers side. Her protective nature and strong ties to her peers define her role within the group dynamic before the combat mission begins. Her role in the story is tragically brief. Before the students can even begin their assigned mission to hunt down Shuya Nanahara, they are transported by boat to the battlefield. During this initial approach, the terrorist group known as the Wild Seven launches a surprise assault on the students boats. During this attack, a bullet strikes Ayane in the left arm, incapacitating her. As she lies injured near another student, Hibiki Yano, a rocket-propelled grenade is fired towards their vessel. The resulting explosion destroys the boat, killing Ayane and all other students on board, making her one of the very first casualties of the program. Her death is abrupt and highlights the chaotic and indiscriminate violence of the opening mission. While she shows a willingness to protect her friends, her notable abilities are not combat-oriented; instead, her defining characteristics are her resilience in the face of past trauma and her fierce loyalty to her small group of friends, specifically Kana Yuki, as demonstrated through her protective actions in the cage and her emotional bonds formed through the basketball club and local community ties.