Prologue/Reincarnation Arc

An obstetric doctor and an idol fan are killed and reincarnated as twins born to the idol Ai Hoshino, beginning their unexpected new lives with memories of their past.

The Prologue and Reincarnation arc establishes the extraordinary premise of Oshi no Ko. Gorou Amamiya, a talented obstetric doctor, and Ai Hoshino's most devoted fan meet in Ai's hospital and are killed in a tragic accident. They are mysteriously reincarnated as Aqua and Ruby Hoshino, twin children born to Ai Hoshino herself. Retaining memories of their previous lives, the twins must navigate their new existence as idol children while understanding their impossible situation. The arc balances the shock of their reincarnation with Aqua and Ruby's gradual adjustment to their new circumstances. The arc also introduces Ai Hoshino's murdered state—the mystery that will drive the entire series forward. Aqua discovers that their mother did not die a natural death but was deliberately murdered, setting him on a path to uncover the truth.