Waya was forced to transfer schools due to his parents' circumstances. His mother, Kei, worried whether he would adapt well to his new environment, but her concerns quickly proved unfounded when he soon invited his new friend, Koji, over to their home. Polite, well-mannered, and excelling both academically and athletically, Koji gradually earned Kei's trust, and she began growing more affectionate toward him. However, this growing closeness would soon lead to unforeseen complications. One day, jokingly, Kei said, "Maybe I should become Koji-kun's girlfriend." That single remark unexpectedly stirred something deep within Koji. From that moment on, an unexpected turn of events begins, culminating in intimate encounters filled with creampie passion between the married woman and her son's friend.