Step-sisters Saya and Hinata share a forbidden romance that is discovered by the opportunistic Tachikawa of the Photography Club. Using the secret as leverage, Tachikawa blackmails the pair into filming explicit videos, forcing them into increasingly degrading sexual encounters to protect one another. As the sisters succumb to the blackmail, their lives spiral into a cycle of abuse and public humiliation, culminating in a massive, coordinated filming event involving numerous male students.