Minami is consumed by jealousy after her father remarries, feeling replaced by her new stepmother. Unable to sleep late at night, she hears eerie sounds coming from her parents' bedroom. Haunted by the noises, her imagination runs wild. One night, she suddenly wakes up and heads to the bathroom. Passing by her father's room, she peeks through a slightly opened door and sees the stepmother kneeling on the floor, her buttocks exposed, being whipped while hot wax is dripped onto her skin, with a beaded vibrator inserted deep inside. The next day, her father leaves for an overnight golf trip and the stepmother goes out for a class reunion, leaving the house empty. Curious, Minami enters her father's bedroom and checks the closet—there, she discovers hidden BDSM equipment. She stands frozen in place, trembling with overwhelming shock.