Monica Lux is one of the main protagonists in the new Netflix series Lost Song and the younger sister of Allu. Her trademark is her bunny-hooded cloak. She pulls the hood over her head and falls asleep any time she is frightened, and is often mistaken for a "weird creature".
Monica traveled with Allu as rhythmists of the king's military for moral support. They are first seen while playing their instruments for military personnel who were making echo devices. They were doing what they could in order to make money to restore their mother's eyesight. With Monica's help, Rin sings the Song of Healing, restoring her mother's eyesight. Eventually the sisters join Rin and her friends' journey to the capital.