Something About 1% is a romantic comedy about a wealthy heir named Lee Jae In who must enter into a contract relationship with a strong-willed school teacher named Kim Da Hyun. Despite their initial dislike for each other, they gradually develop a love-hate relationship filled with misunderstandings and comical moments.

Kim Jung-Hwa is a young and kind middle school teacher with little interest in money. When she helps carry an elderly man's belongings, who is extremely thankful to her. This grandfather turns out to be rich and an owner of a well-known conglomerate. His grandson, Kang Dong-Won is a quick-tempered businessman who butts heads with his grandfather. To "tame" his favorite grandson, the grandfather agrees to give his entire fortune to the person who marries Jung-Hwa, forcing Dong-won to meet the girl. Although at first Jung-Hwa and Dong-won don't get along because of Dong-won's bad temper, their arguments bring them closer together. Dong-won starts to get jealous when Jung-Hwa's fellow teacher starts liking her too. However, what looked like a relationship that would 99% not work out, turns out to be the "perfect" match, the 1% chance.