A young aspiring model and singer named Ai Asaka is on the verge of a breakthrough. With the dedicated support of her manager, Bando, she secures a major record deal to launch her music career. The song she is to perform is a haunting ballad titled Yume Nara Samete, written by her late friend, Hiromi, who died by suicide shortly after composing it. The song is Hiromi's final confession of love for a married teacher, and Ai carries the weight of this tragedy as she steps into the spotlight.

As Ai’s public profile begins to rise, she crosses paths with Toshihiko Horibe, a timid clerk at a local convenience store. Horibe is not just a casual admirer; he is a dangerously obsessed fan who has spent years meticulously copying every detail of Ai’s life. He reveals that he has been "living her life" since they were children, going so far as to replicate her former apartment exactly. His obsession takes a bizarre and unsettling physical turn due to a medical condition that causes his body to overproduce estrogen. As a result, Horibe begins a slow, physical metamorphosis, becoming an identical doppelgänger of Ai. Convinced that Ai is "not the true Ai," he decides that he must replace her entirely to become the real star.

Ai finds her world collapsing under the pressure of her stalker’s actions and the unresolved grief over her friend’s death. As Horibe’s delusions grow stronger, the line between reality and his twisted fantasy blurs. Just as he prepares to enact his plan to usurp Ai’s identity, the confrontation reaches a sudden and violent end. Horibe is killed in a knife attack. The assailant is revealed to be Bando’s seemingly unassuming wife. Driven by a jealous rage over her husband’s obsessive mentoring of Ai, she eliminates the young singer’s tormentor, with strong implications that she was also responsible for the murder of Bando’s previous idol client years earlier.