Nitta, whose wife is due to give birth in a week, is visiting his hometown when he meets Yuna (married), the most popular girl at his high school, at a reunion. The two hit it off and, since neither of them had sex, they cross the line. From that day on, Nitta's days of being milked of his sperm by a devilish woman who mounts his wife, steals her and makes her cum inside him...