“I never even got to confess… and now I’ve become his bed partner.” Sejin, a high school teacher living an ordinary life, unexpectedly reunites with Juhwan — her unrequited love from college — when he returns as the acting chairman of her school’s foundation. While Sejin’s calm life starts to crumble with his sudden reappearance, Juhwan doesn’t even recognize her. A few days later, they meet again at a reunion, and the night ends in a moment of impulsive passion. Telling herself it was just closure for her long-time crush, Sejin plans to end it there — but intrigued by her, Juhwan proposes a three-month partnership instead… A realistic romance between two people whose one-night stand turns their relationship upside down.