日本伦理片《優しい姉妹：夫交換の日》讲述Saya, who had trouble getting her boyfriend full of stamina, tells her cousin Marie that it is too hard. At that time, Marie gives her young couple an extraordinary suggestion of swapping their married couple, telling them about their sex. The special sex education of the married couple with the technique of the anniversary begins now.影片由内详等主演。
