Welcome to a female prison in a dark society in which prisoners are ruled by sexual pressure. The new inmate Marina has been severely harassed by Iona in her cell and sadistic guard Natasha. One day she tries to jailbreak with the mysterious prisoner Kaede and others, but fails unfortunately. Anyone trying to escape from prison in this prison is immediately sentenced to death. However, only those who survive the forbidden game, "Unlimited Strip Mahjong", can escape the punishment. Marina and the others start a game of Mahjong to save their lives....