Based on the Japanese drama 'Proposal Daisakusen' comes the story of a man who regrets never telling his best friend that he's in love with her on the day of her wedding. Yoo Seung Ho (God of Study, Flames of Desire) and Park Eun Bin (Queen Seon Duk) reunite onscreen as the fated couple. Lee Hyun Jin (Heartstrings) and Kim Ye Won (Flower Boy Ramen Shop) round out this youthful cast in this fantasy melodrama. Kang Baek Ho (Yoo Seung Ho) has been friends with Ham Yi Seul (Park Eun Bin) for the past twenty years, but has never mustered enough courage to tell her that he loves her. Now, on Valentine's Day, it might be too late. He races to Yi Seul's wedding as her "man of honor," and watches her marry another man, Kwon Jin Won (Lee Hyun Jin). Full of regret, Baek Ho wishes desperately that he could have done things in the past differently. Enter the Conductor (Kim Tae Hoon) - the man who can help fulfill Baek Ho's deepest desire. He can control time, and so he sends Baek Ho all the way back to high school for another chance at taking control of his own destiny, and possibly changing his future. A sweet, youthful melodrama, Operation Proposal asks the question: If you had another chance for a do-over, would you do anything differently?