A sadistic futa-nari kidnaps a desperate sister for her own pleasure, forcing her into an obedient submission that can't be easily reversed.
Meet Karin, who fell victim to a cunningly planned trap. Her younger brother was kidnapped, and in order to get him back, she must submit to the futa-nari invader, Chika. At first, she resists and tries to escape but soon finds herself helplessly obeying her captor's orders. As the days pass, Karin begins to succumb to her lustful desires. She is dominated by a colossal phallus with futa-nari qualities that overwhelms her both physically and mentally. The more she resists, the deeper she falls into Chika's clutches. Will she ever be able to break free from this sexual slavery?