When his father remarried, his son Yusei didn't like his new mother Mako. One day, Yusei raped Mako and filmed the rape on his phone, then used the footage to blackmail her and train her to be a titty-fuck sex slave. Yusei's training escalates, and while his father is away, he and his delinquent senior restrain Mako and make her cum over and over with an electric massager and a vibrator, then he and his senior with a big dick continue to rape Mako's huge tits. Mako gradually goes crazy with pleasure.