[OSHI NO KO] Ruby Hoshino「星ほし野の瑠る美び衣い, Hoshino Rubii?」, more commonly referred to as just Ruby「ルビー, Rubī?」, is the female protagonist and one of the titular characters of the Oshi no Ko manga series. In her previous life, she was known as Sarina Tendouji, a terminally ill patient who was cared for by Gorou Amamiya and, following her death, was reincarnated as the child of her favorite idol, Ai Hoshino. Neglected by her parents in her previous life and being a fan of Ai, she greatly enjoyed her new life, with her new mother teaching her how to be an idol from an early age. Unfortunately, this happy life ended when Ai was murdered by a deranged fan. Afterward, determined to fulfill her mother's dreams, she reforming Ai's idol group with the support of her friends.