Futaro Uesugi is a seventeen-year-old boy, extremely intelligent and studious, but taunted and ostracized by his classmates for his shy and reserved character. One day he has a brief altercation in the cafeteria with Itsuki Nakano, a student who has just transferred to the school; upon returning home, he discovers that he has been hired as a private tutor by the girl's wealthy family of all people. In spite of himself, he discovers that in need of tutoring is not only Itsuki, but also her twin sisters Miku, Ichika, Yotsuba, and Nino, all of whom are at risk of flunking out due to poor grades. Due to his family's precarious economic situation, which leads him to keep expenses down even on meals, Futaro is forced to accept the assignment. He is initially greeted skeptically by the twins, however, as he helps them pass their school exams, Futaro forms a special relationship with each of them.