Mary Skelter: Nightmares Final by Idea Factory - Adult Sex Game

The "Jail" suddenly appeared a number of years ago, sinking the city deep into the ground. There, this impenetrable living prison 666 metres beneath the surface, held power over eerie creatures called "Marchens." Within the prison was a guy named Jack - living a life of suffering, tortured day in and day out, in a world where all dreams, hopes, peace, and humanity had been lost for as long as the people could remember.