One

Rhyth is a 17 year old girl who lives in the Fortified Residential Zone, a walled-in section of city located on the outskirts of Tokyo. She'd been taken there by Rokkaku Goji's Golden Rhinos 10 years prior, supposedly for her own protection. Since day one, her routine has consisted of grueling training and bland, uninspiring food. However, one day, the strange head band her mother had sent her off with starts making a mysterious noise...

This signal to the Fortified Residential Zone holds the key to changing her future, as well as to discovering what she actually is...