Gorou Amamiya, a small-town obstetrician, is murdered by a delusional stalker just as he prepares to deliver the twin babies of his favorite idol, Ai Hoshino. Upon death, Gorou is reincarnated as Aquamarine Hoshino, one of Ai’s newborn twins, while a dying young patient of his, Sarina, is reborn as his twin sister, Ruby. They retain their memories, forced to navigate infancy while fiercely supporting their mother's skyrocketing idol career. Tragedy strikes when Ai is brutally murdered on her birthday by the same deranged stalker, who learned of her secret family. This devastation alters Aqua’s psyche; realizing the killer must have had inside information, Aqua vows vengeance, deducing that his biological father—an industry insider—orchestrated the assassination.Years later, Aqua and Ruby enter the
entertainment industry. Ruby dreams of becoming an idol like Ai, eventually forming a new group with MEM-cho and the talented child actress Kana Arima. Meanwhile, Aqua uses his acting career as a calculated tool for revenge. He infiltrates the acting world, manipulating directors, reality TV producers, and stage plays to get closer to high-ranking industry figures, particularly suspected theater directors connected to his mother's past. Aqua’s cold pragmatism constantly clashes with his genuine protective instincts toward Ruby and Kana, the latter of whom harbors unrequited romantic feelings for him.The narrative darkens during a theatrical arc adapting a notorious manga, where Aqua’s past trauma resurfaces, triggering severe panic attacks and forcing him to confront the
psychological abyss of his guilt over failing to save Ai. Simultaneously, Ruby undergoes a chilling personality shift upon discovering the truth about Gorou’s murder, inheriting Ai’s uncanny star eyes and abandoning her naive optimism for a ruthlessly ambitious path to stardom.As the story progresses, Aqua uncovers the identity of his biological father: Hikaru Kamiki, a charismatic, manipulative actor with a trail of dead young starlets in his wake. Aqua devises an intricate, high-stakes revenge plot, writing a feature film explicitly detailing Ai's murder to lure Kamiki into the open. He intends to expose him publicly, destroying his life while ensuring his own destruction in the process. Navigating the toxic underbelly of Japanese show business, the siblings push forward—Ruby blinded by vengeance and grief, and Aqua consumed by self-loathing, both hurtling toward a devastating final confrontation with the architect of their family's ruin.