During summer vacation, Yu was staying at his relative's house for a week. However, he couldn't concentrate on his studies due to his aunt Mafuyu's careless appearance. As he masturbated helplessly, she noticed his young and sturdy member and became aroused. She had been unsatisfied with just her husband and decided to release her sexual desires onto him. Overwhelmed by pleasure, Yu lost control and began aggressively fucking her like an animal. To his surprise, Mafuyu found herself getting more and more immersed in their endless incestuous intercourse...

夏期講習で親戚の家に1週間居候する事になったゆう。だが叔母・麻妃の無防備な姿に勉強が手につかず、悶々としながらオナっていると…。彼の若く逞しい肉棒に目を奪われた麻妃は、夫だけで満足できない日々の性欲を彼で発散させるのだった。すると、彼女に襲われて性の目覚めを感じたゆうは、あまりの快楽に我を忘れてサルのように麻妃を犯し始める。終わり無き甥のガムシャラな性交に彼女自身もどんどんのめり込んでしまい…。