A private investigator running a detective agency in Tokyo receives a strange request. It comes from a female apartment owner who claims to be a college student and says she's being stalked. At the client's request, the agency installs hidden cameras in the woman's apartment. A few days later, the footage reveals an unexpected scene: the apartment owner's son casually visiting the college girl's room and repeatedly engaging in lewd behavior toward her with an innocent demeanor. He gropes her big breasts and grows increasingly intimate with her, eventually leading to them having sex. This secret relationship continues to develop in surprising ways, captured entirely on camera.