"If Tomorrow Comes" is a family drama centered around a mother and her daughter.  Yoon Eun-Chae (Seo Woo) is an only child. Her father Yoon Won-Sub (Kil Yong-Woo) owns a mid-size construction company, but his wife Son Jung-In (Ko Du-Shim) actually runs everything in the company. His wife is notorious for doing anything for the family business. Eun-Chae is a graduate student studying interior design. Unlike her mother, she is cute, confident and has a positive outlook on life. Eun-Chae dates Lee Young-Gyun (Ha Seok-Jin).  Lee Young-Gyun is an ordinary salaryman with a good personality. His parents runs a restaurant and he has 4 siblings. His oldest brother has yet to marry, the second oldest brother has a limited mental capacity, the third youngest brother Lee Il-Bong always makes trouble and a younger sister. Lee Young-Gyun and his family has to pay back money that troublemaker Lee Il-Bong caused.  On the day Eun-Chae's mother is scheduled to appear as a TV show guest, Eun-Chae plans to introduce Young-Gyun to her family. Eun-Chae even buys Young-Gyun's outfits for that day and invites him over. When the day arrives, Young-Gyun runs late because he is busy fixing the drain at his parents' restaurant. He rushes over to the TV station and says hello to Eun-Chae's parents. Eun-Chae is disappointed that he isn't wearing the outfit she bought for him. Eun-Chae's mother invites Young-Gyun to her wedding anniversary party.  Meanwhile, Eun-Chae's mother invites other young men, close to Eun-Chae, to her wedding anniversary party. At the party, Eun-Chae's mother makes it clear that Young-Gyun is just a friend of Eun-Chae's, implying that their relationship is over. Young-Gyun is about to leave the party when Eun-Chae grabs Young-Gyun and kisses him in front of the guests.