Mina, who had been bullied by her mother-in-law all along, accidentally injures her in an accident. Panicked, Mina runs away from home and changes her name to Marina Matsumoto, starting to live and work at a factory. Despite being a woman, she works hard labor alongside men and manages to live a peaceful life. However, when a detective comes to the factory looking for Marina, she is blackmailed by a coworker named Fuchigami. If she wants to stay at the factory, she is forced into obscene anal training and ultimately becomes a slave to satisfy the workers' sexual desires…
