Gorou Amamiya, an
obstetrician-gynecologist and admirer of the
pop idol Ai Hoshino, is entrusted with the confidential delivery of her children. On the night of the birth, he is murdered by an obsessive fan of Ai's and is
reincarnated as her son, Aquamarine "Aqua" Hoshino, retaining all memories of his past life. Unbeknownst to him, his fraternal twin sister,
Ruby Hoshino, is the reincarnation of Sarina Tendōji, a deceased patient of Gorou's who also admired Ai. Four years later, Ai is murdered before the twins' eyes by the same fan who killed Gorou. Though the fan subsequently commits suicide, Aqua deduces their biological father may have been an accomplice and resolves to infiltrate the entertainment industry to find and exact revenge upon him. Twelve years later, the twins are high school students adopted by
Miyako Saitō, the head of Ai's former talent agency, Strawberry Productions. Ruby pursues her dream of becoming an idol, forming a new group named B-Komachi with actress
Kana Arima and
YouTuber Mem-cho, while Aqua returns to acting. Aqua leverages his growing network, including a strategic friendship with actress
Akane Kurokawa, to further his investigation. During a stage production, he discovers a shared paternity with his co-star,
Taiki Himekawa, whose father died by suicide before Ai's murder. Through Akane's research, Aqua later identifies the actor
Hikaru Kamiki as their likely father and the mastermind behind the killings. Concurrently, while filming a music video, Ruby discovers Gorou's corpse, learning the truth of his murder and fueling her own desire for vengeance. These parallel discoveries intensify the twins' grudges, but their increasingly manipulative methods to reach Hikaru create a rift between them, culminating in a loss of trust after Aqua deliberately leaks their connection to Ai to the media. With the assistance of director
Taishi Gotanda, Aqua writes an autobiographical screenplay based on Ai's life, titled 15 Years of Lies, intending to lure Hikaru out. Ruby aggressively secures the lead role. During production, a meeting with her previous life's mother, who is a film sponsor, forces a confrontation with her past; this encounter also leads to Aqua and Ruby realizing each other's true reincarnated identities. At the film's debut, Aqua finally makes contact with Hikaru, who confesses to using Ai as an emotional crutch and, in a fit of despair after she left him, manipulating the fan to target her. Aqua reveals Ai's final message, in which she expressed her hope that Hikaru would learn to love himself and that she would have grown to love him in time. Hikaru claims he intends to surrender to authorities, but instead manipulates Nino, a former member of Ai's B-Komachi, into attempting to murder Ruby. The attempt is thwarted by Miyako's husband,
Ichigo, and Akane. Aqua then confronts Hikaru, who reveals his desire to immortalize Ai's beauty by killing anyone who might surpass her. Believing Ruby will never be safe while Hikaru lives and willing to sacrifice his own future, Aqua stabs himself and commits a
murder–suicide with Hikaru by throwing them both off a cliff. He succeeds in drowning Hikaru but succumbs to his own wounds, finding final solace in having protected his sister rather than merely achieving revenge. In the aftermath, Hikaru's crimes are publicly exposed, and his accomplices are arrested. The film is released as a tribute to Aqua, as his friends struggle to cope with his loss and seek new purpose. Ruby, now an idol who embodies the same radiant spirit as Ai, performs at a tribute concert. Though she—like her mother—must conceal her pain behind a performative smile, she finds genuine happiness in her career, thanking her late mother and brother for lighting her path and asking them to watch over her. == Development ==