A modest wife named Kaori, raised in the city, accompanies her husband on his first visit back home since their marriage. On their way to the countryside, her sister-in-law Mio warmly welcomes the couple, but her gaze repeatedly lewdly scans Kaori's body. At first unaware, Kaori gradually begins to notice Mio's increasingly bold behavior. Torn between growing unease and distrust, Kaori finds herself emotionally drawn to her sister-in-law's advances—until ultimately, she is completely consumed by Mio's seduction.