The wife's elder sister came to help with household chores because the wife was hospitalized. The woman, known as Tsuba-san to her brother-in-law, is beautiful and kind-hearted, always ready to help her younger brother-in-law. Living together alone made them grow intimate... Even though she is a married woman with a husband, she repeatedly engages in intense adultery with her sister-in-law during the absence of her niece! She indulges in forbidden pleasure, risking everything to keep it secret!
