One day, Reiko asked her son to bring in the laundry while she went shopping. While doing so, the son picked up his mother's panties and sniffed them. Remembering secretly peeping on his parents having sex the previous night, he masturbated while smelling the panties that evening. When the son left the room, he suddenly heard a voice from behind. Quietly peeking in, he saw Reiko masturbating. The next day, watching his mother clean, the son became fixated on her ass, his urge to masturbate growing stronger. Unable to resist any longer, he attacked Reiko...