Sister-in-law, from now on you are my master. Young wife Yuu is forced every night by her beloved husband's younger brother to experience humiliating pleasure. Though her mind resists, this ecstasy dominates her body, pulling her into an irreversible, profound delight. Accepting the collar handed to her by her brother-in-law, she surrenders herself to the pleasure her body craves. Drawn ever deeper by his sweet words and commanding strength, Yuu becomes increasingly entranced. As if in a dream, her mind sinks further and further into submission.