Gorou Amamiya, a gynecologist and idol fan, is murdered and reincarnated as Aquamarine Hoshino, the newborn son of his favorite idol, Ai Hoshino. Alongside his twin sister Ruby—who is the reincarnation of another patient of Gorou's—Aqua navigates the dazzling yet deeply cutthroat Japanese entertainment industry. Tragedy strikes when Ai is murdered by a stalker, setting Aqua on a dark path of vengeance to find the person responsible, who he believes is his and Ruby's biological father lurking within the industry. As the twins grow older, Aqua enters the world of acting to gather clues, while Ruby strives to follow in her mother's footsteps and become an idol herself, uncovering the toxic realities, dark secrets, and immense pressures hidden behind the glamour of show business.