[Machine Translation] Starring Ji-sung & Han Ji-min! If I could go back to that moment - the only "if" in my life. --Joo-hyuk, a bank employee, has been married for five years to Woo-jin, an esthetician, and is the father of two children. At work, he is blamed by his boss and pushed around by his inflexible subordinates. When he returns home exhausted, his wife Woo-jin curses him. Woo-jin, who was once a sweet girl before they got married, is now always grumpy and takes out her frustrations from work and child-rearing on Joo-hyuk. Joo-hyuk is even contemplating divorce when Hae-won, his junior in college and his first love, appears in front of him. Hae-won is still as kind and beautiful as she was back then. She confesses to him that she used to love him, and Joo-hyuk begins to regret his marriage to Woo-jin even more. One day, while driving on the highway, Joo-hyuk passes through an unfamiliar tollbooth. Suddenly, the car goes out of control, and he finds himself transported back to his college days! Joo-hyuk is confused, but soon after, he collides with a motorcycle, and when he passes out again, he finds himself back in the present day. Juhyeok realizes that the toll booth is suspicious, so he goes through it again, and by saving Woo-jin, he succeeds in going back to "that day" when he broke his promise to Hae-won. Naturally, Juhyeok tries to choose the promise he made to Hae-won. And when he wakes up, it is Hae-won, who has become his wife, who calls out to him kindly! However, in front of the happy-go-lucky Joo-hyuk, Woo-jin, who has become a career woman, appears. Joo-hyuk is puzzled by his attraction to the beautiful Woo-jin, who is also working at the same place. On the other hand, Woo-jin is also confused about her own feelings for Joo-hyuk, who is married. Includes episodes 1-16 (final episode).