Airi Sakura attends Tokyo Metropolitan Advanced Nurturing High School as a Class D student. She has pink hair styled in low twin pigtails, gradient blue eyes, and stands 153 cm tall. Her measurements are B96/W60/H90, making her one of the school's most physically endowed students, though she conceals her figure through slouching and wearing plain clothing. Before high school, Airi worked as a gravure idol using the alias "Shizuku," amassing over 5,000 online followers. School restrictions on external contacts forced her to pause this career, though she continued posting photos anonymously within school guidelines. To avoid recognition, she adopted fake red glasses and changed her hairstyle. Airi exhibits extreme shyness and social anxiety, struggling to communicate with classmates and actively avoiding attention. She frequently retreats to secluded spots like her room or behind school buildings. Despite her timidity, she displays a contrasting lively persona when taking self-portraits as "Shizuku," smiling brightly for the camera. Her sole hobby is photography, and she carries a cherished digital camera. Early in her first year, Airi witnessed Ken Sudō fighting Class C students, inadvertently capturing the incident in a photo. Reluctant to testify due to fear, she was pressured by Kikyō Kushida, who damaged Airi’s camera during a confrontation. After Kiyotaka Ayanokōji advised her to follow her instincts, she agreed to testify, using the photo as evidence. Later, a stalker—an electronics store clerk who recognized her—harassed her for three months. When he assaulted her on campus, Kiyotaka Ayanokōji and Honami Ichinose intervened, leading to the stalker’s arrest. This incident prompted Airi to discard her glasses, embrace her appearance, and develop romantic feelings for Kiyotaka. She joined the "Ayanokōji Group" to socialize more, bonding closely with Haruka Hasebe, who teased her about her crush. Airi gradually attempted self-improvement. During a first-year pool outing, she wore a rash guard to hide her body but switched to a revealing bikini in her second year, signifying growing confidence. She practiced confessing to Kiyotaka during a school cruise but hesitated when he appeared. She also gave him Valentine’s Day chocolate, though he began dating Kei Karuizawa. Academically, Airi ranked lowest in her class per the OAA system, with scores of Academic Ability: C (50), Physical Ability: D- (25), Thinking: D- (25), and Social Contribution: C+ (60), totaling 36 points. During a second-year exam requiring class expulsion, Kiyotaka objectively nominated her due to her low OAA. Haruka, Akito, and Keisei opposed this, but 37 classmates voted against her expulsion. Airi was expelled after a revote, fracturing the Ayanokōji Group. Post-expulsion, Airi planned to confess to Kiyotaka but faced his transfer to another class. Haruka and Akito confronted him about abandoning the group, with Akito noting Airi’s unresolved feelings.