Female Solitary Confinement Prison.

Reiko wakes up in a prison cell only to discover that, for some reason, she has been incarcerated in Chibajiri Women’s Prison under a life sentence using the identity and criminal record of a complete stranger named Manami Sano. To uncover the meaning of the mysterious “××” carved into her arm, and unravel the truth behind everything that has happened, she accepts life as the woman known as Sano.