Nao, an employee at a life insurance company, begins investigating the accidental death of a young man and stumbles upon the sudden disappearance of a girl named Reina, who was once bright and cheerful. To uncover the truth, Nao travels with associates Kasumi and Sara to the remote Slave Island. Upon arrival, Nao is shocked by Reina's appearance—her condition far beyond a simple disappearance, showing signs of extreme transformation. Soon, Nao herself begins to be treated as a slave, and her life on the island gradually descends into distortion and depravity.