Ai Hoshino begins her life in difficult circumstances, having grown up in an orphanage after being abandoned by her mother. It was there that she was scouted at the age of twelve by Ichigo Saitou, the president of Strawberry Productions, who saw the potential for her to become a star. Despite her initial doubts about being an idol because she felt incapable of understanding love, she took his advice to use lies as a tool to connect with her audience, hoping that one day those lies would become the truth. This philosophy defines her entire public persona; she becomes a consummate liar who portrays an illusion of perfection and happiness to her fans, a skill she wields with exceptional talent and charisma.

Ai’s personality is a study in contrasts. To the world, she is a radiant and captivating pop idol, the unchallenged centerpiece of the group B-Komachi, whose beauty, talent, and magnetic stage presence mesmerize the entire country. She is often seen as an airhead who is bad with names and faces, adding to her charming public image. However, this facade conceals a deeply troubled inner world. Beneath her cheerful smile, she is haunted by the fear that she is incapable of genuine love, a conviction born from her abusive and unstable childhood. Her backstory includes not only abandonment but also the threat of sexual abuse from her mother’s boyfriend, which contributed to her emotional instability. She sees herself as broken and is terrified that even her love for her own children might be another lie. This internal conflict drives her actions, as she desperately wants to experience true love and break the cycle of bad parenting she endured.

At just sixteen years old, Ai becomes secretly pregnant with twins, Aquamarine and Ruby, a situation that could destroy her idol career. Choosing to have the children, she takes a brief hiatus and becomes a young mother, determined to create the family she never had. The father is revealed to be Hikaru Kamiki, a young man with a similarly traumatic past whom she met through the entertainment industry. Their relationship was intense, as they were kindred spirits who understood each other’s pain and reliance on lies. However, Ai ultimately breaks up with him harshly. While later it is understood this was a cruel-to-be-kind act of love, as she feared her pregnancy would be an unbearable burden for him given his own deep trauma, Hikaru perceived it as a complete rejection.

Her role in the story is that of a posthumous, driving force. Her tragic murder at the age of twenty, stabbed by an obsessed fan who was enabled by Hikaru, is the catalyst for the entire plot. She is the central figure whose death her children swear to avenge; Aqua dedicates his second life to finding and punishing those responsible, while Ruby strives to follow in her footsteps as an idol. Her relationships with her children are the most significant aspect of her development. For years, she is unable to tell them "I love you," fearing the words would be hollow. It is only in her final moments, as she lies dying, that she is able to sincerely express her love for Aqua and Ruby, finally understanding that her love for them is real. This realization is her ultimate emotional breakthrough.

Ai’s most notable abilities lie not in a specific skill but in her overwhelming presence and emotional intelligence. She possesses an almost supernatural charisma on stage, often depicted with six-pointed stars in her eyes, a trait she passes to her children. Her true genius is her ability to lie so perfectly that she becomes the ideal idol, an invincible figure of adoration. She is also incredibly brave, deciding to become a mother and continue her career despite the immense personal and professional risks, knowing it could lead to her ruin. Through her brief life, Ai Hoshino is transformed from a girl who thought she could not love into a person whose desperate search for love and family becomes the emotional core that sets the entire tragedy of Oshi no Ko into motion.