Lost Song is the story of two female singers - Rin and Finis. Rin is a carefree girl who grew up in a small village and was trained to hide her enchanting voice. Finis is a reserved artist who lives in a grand castle. Rin's life takes a turn after she uses her voice to help an injured knight named Henry Leobort. When the army finds out about her talent, they attack her village and try to capture her. In response, Rin and her genius inventor brother Al embark on a journey to the city. Meanwhile, as war approaches, Finis worries about her relationship with Henry. She knows that Prince Lood Bernstein IV desires her, but she is hesitant to use her singing ability to aid him because she fears he will misuse her talents in battle. As they both face uncertain futures, we are left to wonder if and when Rin and Finis will cross paths.