Sister Minami is burdened with overwhelming debt, and her younger sister Ruka has been made a co-signer. One day, Ruka is confronted at home by a group of men in black suits who show her a video message. In it, she sees her sister Minami being helplessly raped in front of her husband. The men reveal that Minami has been kidnapped and imprisoned by a secret underground organization tied to her creditors. Soon after, Ruka is abducted and taken to a foul-smelling underground facility. There, she is reunited with Minami—but instead of safety, she finds herself thrust onto a stage of madness filled with applause, cheers, and the guttural moans of men, where both sisters are forced into a nightmarish world of sexual slavery.