OBA-101 My little sister's tutor Sayuri Obasan Sayuri Naiinu

Sayuri was asked by her older brother, Ichiro, to become a tutor, saying, "I want Haruna, the daughter of an exam student, to teach me to study." In the midst of this, she had a man who seemed to be having a good time. That is Haruna's older brother, Shinya. That was 5 years ago...Shinya, who was also a private tutor for Sayuri, couldn't forget Sayuri's intelligent profile even now. One day, Sayuri sees through her affection for her aunt. And Sayuri takes an unexpected action against Shinya...