Hoping to get rich, Eunje signs a contract for a high-paying tutoring gig, thinking she just hit the jackpot. Expecting to find a cute middle schooler, she's shocked to discover she'll be tutoring her former classmate and man of her nightmares, Sooin! With his harsh way of speaking and rough manners, she is doubly surprised to find that when they're alone, he's not so bad. Will Eunje get to teach some simple math in peace, or will Sooin's hidden soft side give her a quick lesson in love instead?