Fuutarou Uesugi is a top-tier high school student, but his life is far from easy. His aloof demeanor and tendency to keep to himself have left him without friends, and his father's heavy debts force the family to struggle just to get by.
One day during lunch, Uesugi gets into an argument with a female transfer student who takes "his seat," creating mutual dislike between them. Later that same day, he receives a golden chance to wipe out his family's debt: a private tutoring job for a wealthy family's daughter, paying five times the usual rate. He accepts the offer, only to be horrified when he learns the client, Itsuki Nakano, is the very girl he clashed with earlier.
After failing to mend fences with Itsuki, Uesugi realizes his troubles are just beginning: Itsuki is actually one of quintuplets. In addition to her, he must also tutor her sisters—Miku, Yotsuba, Nino, and Ichika—who, despite being in real danger of failing their classes, want nothing to do with a tutor. But with his family's survival on the line, Uesugi presses on, determined to overcome the sisters' hatred for studying and successfully guide them to graduation.