Hitozuma kantsû: Oshioki kankinzeme (2005)

Noriko is a full-time housewife living a happy family life. Seeking a bit of excitement, she occasionally engages in an affair with Takuya, a tennis school coach. One day, while leaving a hotel after a tryst, the two are abducted and held captive by an unknown party. The kidnapper, speaking through a voice changer, tells them, "If you can figure out the reason for your confinement, I’ll let you go." As Noriko remains unable to fathom the motive, she is subjected to a series of punishments...