While her husband is away, her father-in-law ruthlessly thrusts his large cock into her! Regardless of safe or dangerous days, he commands her to spread her legs, telling Minato Riku, "This is special training—to create a body that's easy to get pregnant." Desperate to have a child, Riku obeys his words. Day after day, she is tormented by her father-in-law, until eventually she starts craving the training herself. Her relationship with her father-in-law grows deeper, transforming both her body and mind.